Nouveau - Aug 2020 - [RFC 13/20] drm/i915/dp: Extract drm_dp_downstream_read_info()

To start off: this patch series is less work to review then it looks -
most (but not all) of the nouveau related work has already been reviewed
elsewhere. Most of the reason I'm asking for an RFC here is because this
code pulls a lot of code out of i915 and into shared DP helpers.

Anyway-nouveau's HPD related code has been collecting dust for a while.
Other then the occasional runtime PM related and MST related fixes,
we're missing a lot of nice things that have been added to DRM since
this was originally written. Additionally, the code is just really
unoptimized in general:

* We handle connector probing in the same context that we handle short
  IRQs in for DP, which means connector probing could potentially block
  ESI handling for MST
* When we receive a hotplug event from a connector, we reprobe every
  single connector instead of just the connector that was hotplugged
* Additionally because of the above reason, combined with the fact I had
  the bad idea of reusing some of the MST locks when I last rewrote
  nouveau's DP MST detection, trying to handle any other events that
  require short HPD IRQs is a bit awkward to actually implement.
* We don't actually properly check whether EDIDs change or not when
  reprobing, which means we basically send out a hotplug event every
  single time we receive one even if nothing has changed

Additionally, the code for handling DP that we have in nouveau is also
quite unoptimized in general, doesn't use a lot of helpers that have
been added since it was written, and is also missing quite a number of
features:

* Downstream port capability probing
* Extended DPRX cap parsing
* SINK_COUNT handling for hpd on dongles

Luckily for us - all of these are implemented in i915 already. Since
there's no reason for us to reinvent the wheel, and having more shared
code is always nice, I decided to take the opportunity to extract the
code for all of these features from i915 into a set of core DP helpers,
which both i915 and nouveau (and hopefully other drivers in the future)
can use.

As well, this patch series also addesses the other general
connector probing related issues I mentioned above, along with rewriting
how we handle MST probing so we don't hit any surprise locking design
issues in the future.

As a note - most of this work is motivated by the fact that I'm
planning on adding max_bpc/output_bpc prop support, DSC support (for
both MST and SST, along with proper helpers for handling bandwidth
limitations and DSC), and fallback link retraining. I figured I might as
clean this code up and implement missing DP features like the ones
mentioned here before moving on to those tasks.

Also, I'm intending for this patch series to get merged through
drm-misc-next. Once that happens, upstream maintainers will probably
have an easier time with merging if they pull the pending patches for
nouveau from Ben's tree before merging drm-misc-next.

Lyude Paul (20):
  drm/nouveau/kms: Fix some indenting in nouveau_dp_detect()
  drm/nouveau/kms/nv50-: Remove open-coded drm_dp_read_desc()
  drm/nouveau/kms/nv50-: Just use drm_dp_dpcd_read() in nouveau_dp.c
  drm/nouveau/kms/nv50-: Use macros for DP registers in nouveau_dp.c
  drm/nouveau/kms: Don't clear DP_MST_CTRL DPCD in nv50_mstm_new()
  drm/nouveau/kms: Search for encoders' connectors properly
  drm/nouveau/kms/nv50-: Use drm_dp_dpcd_(readb|writeb)() in
    nv50_sor_disable()
  drm/nouveau/kms/nv50-: Refactor and cleanup DP HPD handling
  drm/i915/dp: Extract drm_dp_has_mst()
  drm/nouveau/kms: Use new drm_dp_has_mst() helper for checking MST caps
  drm/nouveau/kms: Move drm_dp_cec_unset_edid() into
    nouveau_connector_detect()
  drm/nouveau/kms: Only use hpd_work for reprobing in HPD paths
  drm/i915/dp: Extract drm_dp_downstream_read_info()
  drm/nouveau/kms/nv50-: Use downstream DP clock limits for mode
    validation
  drm/i915/dp: Extract drm_dp_has_sink_count()
  drm/i915/dp: Extract drm_dp_get_sink_count()
  drm/nouveau/kms/nv50-: Add support for DP_SINK_COUNT
  drm/nouveau/kms: Don't change EDID when it hasn't actually changed
  drm/i915/dp: Extract drm_dp_read_dpcd_caps()
  drm/nouveau/kms: Start using drm_dp_read_dpcd_caps()

 drivers/gpu/drm/drm_dp_helper.c             | 150 ++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c     | 130 ++-------
 drivers/gpu/drm/i915/display/intel_dp.h     |   1 -
 drivers/gpu/drm/i915/display/intel_lspcon.c |   2 +-
 drivers/gpu/drm/nouveau/dispnv04/dac.c      |   2 +-
 drivers/gpu/drm/nouveau/dispnv04/dfp.c      |   7 +-
 drivers/gpu/drm/nouveau/dispnv04/disp.c     |  24 +-
 drivers/gpu/drm/nouveau/dispnv04/disp.h     |   4 +
 drivers/gpu/drm/nouveau/dispnv04/tvnv04.c   |   2 +-
 drivers/gpu/drm/nouveau/dispnv04/tvnv17.c   |   2 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c     | 308 +++++++++++---------
 drivers/gpu/drm/nouveau/nouveau_connector.c | 132 ++++-----
 drivers/gpu/drm/nouveau/nouveau_connector.h |   1 +
 drivers/gpu/drm/nouveau/nouveau_display.c   |  72 ++++-
 drivers/gpu/drm/nouveau/nouveau_display.h   |   3 +-
 drivers/gpu/drm/nouveau/nouveau_dp.c        | 201 ++++++++++---
 drivers/gpu/drm/nouveau/nouveau_drm.c       |   4 +-
 drivers/gpu/drm/nouveau/nouveau_drv.h       |   2 +
 drivers/gpu/drm/nouveau/nouveau_encoder.h   |  48 ++-
 include/drm/drm_dp_helper.h                 |  15 +-
 include/drm/drm_dp_mst_helper.h             |  22 ++
 21 files changed, 741 insertions(+), 391 deletions(-)

-- 
2.26.2

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 8a0f7994e1aeb..ee778ddc95fae 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -76,10 +76,10 @@ nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
 	nv_encoder->dp.link_nr = dpcd[2] & DP_MAX_LANE_COUNT_MASK;
 
 	NV_DEBUG(drm, "display: %dx%d dpcd 0x%02x\n",
-		     nv_encoder->dp.link_nr, nv_encoder->dp.link_bw, dpcd[0]);
+		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw, dpcd[0]);
 	NV_DEBUG(drm, "encoder: %dx%d\n",
-		     nv_encoder->dcb->dpconf.link_nr,
-		     nv_encoder->dcb->dpconf.link_bw);
+		 nv_encoder->dcb->dpconf.link_nr,
+		 nv_encoder->dcb->dpconf.link_bw);
 
 	if (nv_encoder->dcb->dpconf.link_nr < nv_encoder->dp.link_nr)
 		nv_encoder->dp.link_nr = nv_encoder->dcb->dpconf.link_nr;
@@ -87,7 +87,7 @@ nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
 		nv_encoder->dp.link_bw = nv_encoder->dcb->dpconf.link_bw;
 
 	NV_DEBUG(drm, "maximum: %dx%d\n",
-		     nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
+		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
 
 	nouveau_dp_probe_oui(dev, aux, dpcd);
 
-- 
2.26.2

Noticed this while going through our DP code - we use an open-coded
version of drm_dp_read_desc() instead of just using the helper, so
change that. This will also let us use quirks in the future if we end up
needing them.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c |  3 ++-
 drivers/gpu/drm/nouveau/nouveau_dp.c        | 30 +++++++--------------
 drivers/gpu/drm/nouveau/nouveau_encoder.h   |  4 ++-
 3 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 7674025a4bfe8..e12957e6faa7c 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -435,7 +435,8 @@ nouveau_connector_ddc_detect(struct drm_connector
*connector)
 
 		switch (nv_encoder->dcb->type) {
 		case DCB_OUTPUT_DP:
-			ret = nouveau_dp_detect(nv_encoder);
+			ret = nouveau_dp_detect(nouveau_connector(connector),
+						nv_encoder);
 			if (ret == NOUVEAU_DP_MST)
 				return NULL;
 			else if (ret == NOUVEAU_DP_SST)
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index ee778ddc95fae..c4e9c21d4dd2b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -36,27 +36,9 @@ MODULE_PARM_DESC(mst, "Enable DisplayPort multi-stream
(default: enabled)");
 static int nouveau_mst = 1;
 module_param_named(mst, nouveau_mst, int, 0400);
 
-static void
-nouveau_dp_probe_oui(struct drm_device *dev, struct nvkm_i2c_aux *aux, u8
*dpcd)
-{
-	struct nouveau_drm *drm = nouveau_drm(dev);
-	u8 buf[3];
-
-	if (!(dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_OUI_SUPPORT))
-		return;
-
-	if (!nvkm_rdaux(aux, DP_SINK_OUI, buf, 3))
-		NV_DEBUG(drm, "Sink OUI: %02hx%02hx%02hx\n",
-			     buf[0], buf[1], buf[2]);
-
-	if (!nvkm_rdaux(aux, DP_BRANCH_OUI, buf, 3))
-		NV_DEBUG(drm, "Branch OUI: %02hx%02hx%02hx\n",
-			     buf[0], buf[1], buf[2]);
-
-}
-
 int
-nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
+nouveau_dp_detect(struct nouveau_connector *nv_connector,
+		  struct nouveau_encoder *nv_encoder)
 {
 	struct drm_device *dev = nv_encoder->base.base.dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
@@ -89,7 +71,13 @@ nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
 	NV_DEBUG(drm, "maximum: %dx%d\n",
 		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
 
-	nouveau_dp_probe_oui(dev, aux, dpcd);
+	ret = drm_dp_read_desc(&nv_connector->aux, &nv_encoder->dp.desc,
+			       drm_dp_is_branch(dpcd));
+	if (ret) {
+		NV_ERROR(drm, "Failed to read DP descriptor on %s: %d\n",
+			 nv_connector->base.name, ret);
+		return ret;
+	}
 
 	ret = nv50_mstm_detect(nv_encoder->dp.mstm, dpcd, nouveau_mst);
 	if (ret == 1)
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h
b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index a72c412ac8b14..6424cdcb4913f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -33,6 +33,7 @@
 #include <drm/drm_dp_mst_helper.h>
 #include "dispnv04/disp.h"
 struct nv50_head_atom;
+struct nouveau_connector;
 
 #define NV_DPMS_CLEARED 0x80
 
@@ -64,6 +65,7 @@ struct nouveau_encoder {
 			struct nv50_mstm *mstm;
 			int link_nr;
 			int link_bw;
+			struct drm_dp_desc desc;
 		} dp;
 	};
 
@@ -104,7 +106,7 @@ enum nouveau_dp_status {
 	NOUVEAU_DP_MST,
 };
 
-int nouveau_dp_detect(struct nouveau_encoder *);
+int nouveau_dp_detect(struct nouveau_connector *, struct nouveau_encoder *);
 enum drm_mode_status nv50_dp_mode_valid(struct drm_connector *,
 					struct nouveau_encoder *,
 					const struct drm_display_mode *,
-- 
2.26.2

Since this actually logs accesses, we should probably always be using
this imho?

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index c4e9c21d4dd2b..8db9216d52c69 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -42,16 +42,12 @@ nouveau_dp_detect(struct nouveau_connector *nv_connector,
 {
 	struct drm_device *dev = nv_encoder->base.base.dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
-	struct nvkm_i2c_aux *aux;
-	u8 dpcd[8];
+	struct drm_dp_aux *aux = &nv_connector->aux;
+	u8 dpcd[DP_RECEIVER_CAP_SIZE];
 	int ret;
 
-	aux = nv_encoder->aux;
-	if (!aux)
-		return -ENODEV;
-
-	ret = nvkm_rdaux(aux, DP_DPCD_REV, dpcd, sizeof(dpcd));
-	if (ret)
+	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
+	if (ret != sizeof(dpcd))
 		return ret;
 
 	nv_encoder->dp.link_bw = 27000 * dpcd[1];
-- 
2.26.2

No functional changes.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 8db9216d52c69..4030806e3522b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -50,11 +50,13 @@ nouveau_dp_detect(struct nouveau_connector *nv_connector,
 	if (ret != sizeof(dpcd))
 		return ret;
 
-	nv_encoder->dp.link_bw = 27000 * dpcd[1];
-	nv_encoder->dp.link_nr = dpcd[2] & DP_MAX_LANE_COUNT_MASK;
+	nv_encoder->dp.link_bw = 27000 * dpcd[DP_MAX_LINK_RATE];
+	nv_encoder->dp.link_nr +		dpcd[DP_MAX_LANE_COUNT] &
DP_MAX_LANE_COUNT_MASK;
 
 	NV_DEBUG(drm, "display: %dx%d dpcd 0x%02x\n",
-		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw, dpcd[0]);
+		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw,
+		 dpcd[DP_DPCD_REV]);
 	NV_DEBUG(drm, "encoder: %dx%d\n",
 		 nv_encoder->dcb->dpconf.link_nr,
 		 nv_encoder->dcb->dpconf.link_bw);
-- 
2.26.2

Since fa3cdf8d0b09 ("drm/nouveau: Reset MST branching unit before
enabling") we've been clearing DP_MST_CTRL before we start enabling
MST.
Since then clearing DP_MST_CTRL in nv50_mstm_new() has been unnecessary
and redundant, so let's remove it.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index e7874877da858..c4d138f0ca054 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1535,17 +1535,6 @@ nv50_mstm_new(struct nouveau_encoder *outp, struct
drm_dp_aux *aux, int aux_max,
 	struct drm_device *dev = outp->base.base.dev;
 	struct nv50_mstm *mstm;
 	int ret;
-	u8 dpcd;
-
-	/* This is a workaround for some monitors not functioning
-	 * correctly in MST mode on initial module load.  I think
-	 * some bad interaction with the VBIOS may be responsible.
-	 *
-	 * A good ol' off and on again seems to work here ;)
-	 */
-	ret = drm_dp_dpcd_readb(aux, DP_DPCD_REV, &dpcd);
-	if (ret >= 0 && dpcd >= 0x12)
-		drm_dp_dpcd_writeb(aux, DP_MSTM_CTRL, 0);
 
 	if (!(mstm = *pmstm = kzalloc(sizeof(*mstm), GFP_KERNEL)))
 		return -ENOMEM;
-- 
2.26.2

While the way we find the associated connector for an encoder is just
fine for legacy modesetting, it's not correct for nv50+ since that uses
atomic modesetting. For reference, see the drm_encoder kdocs.

Fix this by removing nouveau_encoder_connector_get(), and replacing it
with nv04_encoder_get_connector(), nv50_outp_get_old_connector(), and
nv50_outp_get_new_connector().

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv04/dac.c      |  2 +-
 drivers/gpu/drm/nouveau/dispnv04/dfp.c      |  7 +-
 drivers/gpu/drm/nouveau/dispnv04/disp.c     | 18 +++++
 drivers/gpu/drm/nouveau/dispnv04/disp.h     |  4 +
 drivers/gpu/drm/nouveau/dispnv04/tvnv04.c   |  2 +-
 drivers/gpu/drm/nouveau/dispnv04/tvnv17.c   |  2 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c     | 87 +++++++++++++++++----
 drivers/gpu/drm/nouveau/nouveau_connector.c | 14 ----
 drivers/gpu/drm/nouveau/nouveau_encoder.h   |  6 +-
 9 files changed, 105 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv04/dac.c
b/drivers/gpu/drm/nouveau/dispnv04/dac.c
index ffdd447d87068..22d10f3285597 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/dac.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/dac.c
@@ -419,7 +419,7 @@ static void nv04_dac_commit(struct drm_encoder *encoder)
 	helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
 	NV_DEBUG(drm, "Output %s is running on CRTC %d using output %c\n",
-		 nouveau_encoder_connector_get(nv_encoder)->base.name,
+		 nv04_encoder_get_connector(nv_encoder)->base.name,
 		 nv_crtc->index, '@' + ffs(nv_encoder->dcb->or));
 }
 
diff --git a/drivers/gpu/drm/nouveau/dispnv04/dfp.c
b/drivers/gpu/drm/nouveau/dispnv04/dfp.c
index f9f4482c79b54..42687ea2a4ca3 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/dfp.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/dfp.c
@@ -184,7 +184,8 @@ static bool nv04_dfp_mode_fixup(struct drm_encoder *encoder,
 				struct drm_display_mode *adjusted_mode)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
-	struct nouveau_connector *nv_connector =
nouveau_encoder_connector_get(nv_encoder);
+	struct nouveau_connector *nv_connector +	
nv04_encoder_get_connector(nv_encoder);
 
 	if (!nv_connector->native_mode ||
 	    nv_connector->scaling_mode == DRM_MODE_SCALE_NONE ||
@@ -478,7 +479,7 @@ static void nv04_dfp_commit(struct drm_encoder *encoder)
 	helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
 	NV_DEBUG(drm, "Output %s is running on CRTC %d using output %c\n",
-		 nouveau_encoder_connector_get(nv_encoder)->base.name,
+		 nv04_encoder_get_connector(nv_encoder)->base.name,
 		 nv_crtc->index, '@' + ffs(nv_encoder->dcb->or));
 }
 
@@ -591,7 +592,7 @@ static void nv04_dfp_restore(struct drm_encoder *encoder)
 
 	if (nv_encoder->dcb->type == DCB_OUTPUT_LVDS) {
 		struct nouveau_connector *connector -		
nouveau_encoder_connector_get(nv_encoder);
+			nv04_encoder_get_connector(nv_encoder);
 
 		if (connector && connector->native_mode)
 			call_lvds_script(dev, nv_encoder->dcb, head,
diff --git a/drivers/gpu/drm/nouveau/dispnv04/disp.c
b/drivers/gpu/drm/nouveau/dispnv04/disp.c
index 900ab69df7e8f..3f046b917c85c 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/disp.c
@@ -35,6 +35,24 @@
 
 #include <nvif/if0004.h>
 
+struct nouveau_connector *
+nv04_encoder_get_connector(struct nouveau_encoder *encoder)
+{
+	struct drm_device *dev = to_drm_encoder(encoder)->dev;
+	struct drm_connector *connector;
+	struct drm_connector_list_iter conn_iter;
+	struct nouveau_connector *nv_connector = NULL;
+
+	drm_connector_list_iter_begin(dev, &conn_iter);
+	drm_for_each_connector_iter(connector, &conn_iter) {
+		if (connector->encoder == to_drm_encoder(encoder))
+			nv_connector = nouveau_connector(connector);
+	}
+	drm_connector_list_iter_end(&conn_iter);
+
+	return nv_connector;
+}
+
 static void
 nv04_display_fini(struct drm_device *dev, bool suspend)
 {
diff --git a/drivers/gpu/drm/nouveau/dispnv04/disp.h
b/drivers/gpu/drm/nouveau/dispnv04/disp.h
index 495d3284e8766..5ace5e906949a 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/disp.h
+++ b/drivers/gpu/drm/nouveau/dispnv04/disp.h
@@ -6,6 +6,8 @@
 
 #include "nouveau_display.h"
 
+struct nouveau_encoder;
+
 enum nv04_fp_display_regs {
 	FP_DISPLAY_END,
 	FP_TOTAL,
@@ -93,6 +95,8 @@ nv04_display(struct drm_device *dev)
 
 /* nv04_display.c */
 int nv04_display_create(struct drm_device *);
+struct nouveau_connector *
+nv04_encoder_get_connector(struct nouveau_encoder *nv_encoder);
 
 /* nv04_crtc.c */
 int nv04_crtc_create(struct drm_device *, int index);
diff --git a/drivers/gpu/drm/nouveau/dispnv04/tvnv04.c
b/drivers/gpu/drm/nouveau/dispnv04/tvnv04.c
index b701a4d8fe760..3ba7b59580d59 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/tvnv04.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/tvnv04.c
@@ -172,7 +172,7 @@ static void nv04_tv_commit(struct drm_encoder *encoder)
 	helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
 	NV_DEBUG(drm, "Output %s is running on CRTC %d using output %c\n",
-		 nouveau_encoder_connector_get(nv_encoder)->base.name,
+		 nv04_encoder_get_connector(nv_encoder)->base.name,
 		 nv_crtc->index, '@' + ffs(nv_encoder->dcb->or));
 }
 
diff --git a/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
b/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
index 3a9489ed6544f..be28e7bd74903 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
@@ -599,7 +599,7 @@ static void nv17_tv_commit(struct drm_encoder *encoder)
 	helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
 	NV_INFO(drm, "Output %s is running on CRTC %d using output %c\n",
-		nouveau_encoder_connector_get(nv_encoder)->base.name,
+		nv04_encoder_get_connector(nv_encoder)->base.name,
 		nv_crtc->index, '@' + ffs(nv_encoder->dcb->or));
 }
 
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index c4d138f0ca054..71c65f0a68a27 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -411,6 +411,42 @@ nv50_outp_atomic_check(struct drm_encoder *encoder,
 	return 0;
 }
 
+struct nouveau_connector *
+nv50_outp_get_new_connector(struct nouveau_encoder *outp,
+			    struct drm_atomic_state *state)
+{
+	struct drm_connector *connector;
+	struct drm_connector_state *connector_state;
+	struct drm_encoder *encoder = to_drm_encoder(outp);
+	int i;
+
+	for_each_new_connector_in_state(state, connector, connector_state,
+					i) {
+		if (connector_state->best_encoder == encoder)
+			return nouveau_connector(connector);
+	}
+
+	return NULL;
+}
+
+struct nouveau_connector *
+nv50_outp_get_old_connector(struct nouveau_encoder *outp,
+			    struct drm_atomic_state *state)
+{
+	struct drm_connector *connector;
+	struct drm_connector_state *connector_state;
+	struct drm_encoder *encoder = to_drm_encoder(outp);
+	int i;
+
+	for_each_old_connector_in_state(state, connector, connector_state,
+					i) {
+		if (connector_state->best_encoder == encoder)
+			return nouveau_connector(connector);
+	}
+
+	return NULL;
+}
+
 /******************************************************************************
  * DAC
  *****************************************************************************/
@@ -552,16 +588,30 @@ nv50_audio_component_get_eld(struct device *kdev, int
port, int dev_id,
 	struct nouveau_drm *drm = nouveau_drm(drm_dev);
 	struct drm_encoder *encoder;
 	struct nouveau_encoder *nv_encoder;
+	struct drm_connector *connector;
 	struct nouveau_connector *nv_connector;
 	struct nouveau_crtc *nv_crtc;
+	struct drm_connector_list_iter conn_iter;
 	int ret = 0;
 
 	*enabled = false;
+
 	drm_for_each_encoder(encoder, drm->dev) {
 		nv_encoder = nouveau_encoder(encoder);
-		nv_connector = nouveau_encoder_connector_get(nv_encoder);
+
+		drm_connector_list_iter_begin(drm_dev, &conn_iter);
+		drm_for_each_connector_iter(connector, &conn_iter) {
+			if (connector->state->best_encoder == encoder) {
+				nv_connector = nouveau_connector(connector);
+				break;
+			}
+		}
+		drm_connector_list_iter_end(&conn_iter);
+		if (!nv_connector)
+			continue;
+
 		nv_crtc = nouveau_crtc(encoder->crtc);
-		if (!nv_connector || !nv_crtc || nv_encoder->or != port ||
+		if (!nv_crtc || nv_encoder->or != port ||
 		    nv_crtc->index != dev_id)
 			continue;
 		*enabled = nv_encoder->audio;
@@ -572,6 +622,7 @@ nv50_audio_component_get_eld(struct device *kdev, int port,
int dev_id,
 		}
 		break;
 	}
+
 	return ret;
 }
 
@@ -665,7 +716,8 @@ nv50_audio_disable(struct drm_encoder *encoder, struct
nouveau_crtc *nv_crtc)
 }
 
 static void
-nv50_audio_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
+nv50_audio_enable(struct drm_encoder *encoder, struct drm_atomic_state *state,
+		  struct drm_display_mode *mode)
 {
 	struct nouveau_drm *drm = nouveau_drm(encoder->dev);
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
@@ -686,7 +738,7 @@ nv50_audio_enable(struct drm_encoder *encoder, struct
drm_display_mode *mode)
 				     (0x0100 << nv_crtc->index),
 	};
 
-	nv_connector = nouveau_encoder_connector_get(nv_encoder);
+	nv_connector = nv50_outp_get_new_connector(nv_encoder, state);
 	if (!drm_detect_monitor_audio(nv_connector->edid))
 		return;
 
@@ -723,7 +775,8 @@ nv50_hdmi_disable(struct drm_encoder *encoder, struct
nouveau_crtc *nv_crtc)
 }
 
 static void
-nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
+nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_atomic_state *state,
+		 struct drm_display_mode *mode)
 {
 	struct nouveau_drm *drm = nouveau_drm(encoder->dev);
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
@@ -752,7 +805,7 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct
drm_display_mode *mode)
 	int ret;
 	int size;
 
-	nv_connector = nouveau_encoder_connector_get(nv_encoder);
+	nv_connector = nv50_outp_get_new_connector(nv_encoder, state);
 	if (!drm_detect_hdmi_monitor(nv_connector->edid))
 		return;
 
@@ -798,7 +851,7 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct
drm_display_mode *mode)
 		+ args.pwr.vendor_infoframe_length;
 	nvif_mthd(&disp->disp->object, 0, &args, size);
 
-	nv50_audio_enable(encoder, mode);
+	nv50_audio_enable(encoder, state, mode);
 
 	/* If SCDC is supported by the downstream monitor, update
 	 * divider / scrambling settings to what we programmed above.
@@ -1573,7 +1626,8 @@ nv50_sor_update(struct nouveau_encoder *nv_encoder, u8
head,
 }
 
 static void
-nv50_sor_disable(struct drm_encoder *encoder)
+nv50_sor_disable(struct drm_encoder *encoder,
+		 struct drm_atomic_state *state)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_crtc *nv_crtc = nouveau_crtc(nv_encoder->crtc);
@@ -1601,7 +1655,8 @@ nv50_sor_disable(struct drm_encoder *encoder)
 }
 
 static void
-nv50_sor_enable(struct drm_encoder *encoder)
+nv50_sor_enable(struct drm_encoder *encoder,
+		struct drm_atomic_state *state)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_crtc *nv_crtc = nouveau_crtc(encoder->crtc);
@@ -1625,7 +1680,7 @@ nv50_sor_enable(struct drm_encoder *encoder)
 	u8 proto = NV507D_SOR_SET_CONTROL_PROTOCOL_CUSTOM;
 	u8 depth = NV837D_SOR_SET_CONTROL_PIXEL_DEPTH_DEFAULT;
 
-	nv_connector = nouveau_encoder_connector_get(nv_encoder);
+	nv_connector = nv50_outp_get_new_connector(nv_encoder, state);
 	nv_encoder->crtc = encoder->crtc;
 
 	if ((disp->disp->object.oclass == GT214_DISP ||
@@ -1652,7 +1707,7 @@ nv50_sor_enable(struct drm_encoder *encoder)
 			proto = NV507D_SOR_SET_CONTROL_PROTOCOL_SINGLE_TMDS_B;
 		}
 
-		nv50_hdmi_enable(&nv_encoder->base.base, mode);
+		nv50_hdmi_enable(&nv_encoder->base.base, state, mode);
 		break;
 	case DCB_OUTPUT_LVDS:
 		proto = NV507D_SOR_SET_CONTROL_PROTOCOL_LVDS_CUSTOM;
@@ -1693,7 +1748,7 @@ nv50_sor_enable(struct drm_encoder *encoder)
 		else
 			proto = NV887D_SOR_SET_CONTROL_PROTOCOL_DP_B;
 
-		nv50_audio_enable(encoder, mode);
+		nv50_audio_enable(encoder, state, mode);
 		break;
 	default:
 		BUG();
@@ -1706,8 +1761,8 @@ nv50_sor_enable(struct drm_encoder *encoder)
 static const struct drm_encoder_helper_funcs
 nv50_sor_help = {
 	.atomic_check = nv50_outp_atomic_check,
-	.enable = nv50_sor_enable,
-	.disable = nv50_sor_disable,
+	.atomic_enable = nv50_sor_enable,
+	.atomic_disable = nv50_sor_disable,
 };
 
 static void
@@ -2066,7 +2121,7 @@ nv50_disp_atomic_commit_tail(struct drm_atomic_state
*state)
 			  outp->clr.mask, outp->set.mask);
 
 		if (outp->clr.mask) {
-			help->disable(encoder);
+			help->atomic_disable(encoder, state);
 			interlock[NV50_DISP_INTERLOCK_CORE] |= 1;
 			if (outp->flush_disable) {
 				nv50_disp_atomic_commit_wndw(state, interlock);
@@ -2105,7 +2160,7 @@ nv50_disp_atomic_commit_tail(struct drm_atomic_state
*state)
 			  outp->set.mask, outp->clr.mask);
 
 		if (outp->set.mask) {
-			help->enable(encoder);
+			help->atomic_enable(encoder, state);
 			interlock[NV50_DISP_INTERLOCK_CORE] = 1;
 		}
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
index e12957e6faa7c..1d5696c39792a 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -391,20 +391,6 @@ find_encoder(struct drm_connector *connector, int type)
 	return NULL;
 }
 
-struct nouveau_connector *
-nouveau_encoder_connector_get(struct nouveau_encoder *encoder)
-{
-	struct drm_device *dev = to_drm_encoder(encoder)->dev;
-	struct drm_connector *drm_connector;
-
-	list_for_each_entry(drm_connector, &dev->mode_config.connector_list,
head) {
-		if (drm_connector->encoder == to_drm_encoder(encoder))
-			return nouveau_connector(drm_connector);
-	}
-
-	return NULL;
-}
-
 static void
 nouveau_connector_destroy(struct drm_connector *connector)
 {
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h
b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index 6424cdcb4913f..b0e1dad2367d6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -113,7 +113,11 @@ enum drm_mode_status nv50_dp_mode_valid(struct
drm_connector *,
 					unsigned *clock);
 
 struct nouveau_connector *
-nouveau_encoder_connector_get(struct nouveau_encoder *encoder);
+nv50_outp_get_new_connector(struct nouveau_encoder *outp,
+			    struct drm_atomic_state *state);
+struct nouveau_connector *
+nv50_outp_get_old_connector(struct nouveau_encoder *outp,
+			    struct drm_atomic_state *state);
 
 int nv50_mstm_detect(struct nv50_mstm *, u8 dpcd[8], int allow);
 void nv50_mstm_remove(struct nv50_mstm *);
-- 
2.26.2

Just use drm_dp_dpcd_(readb|writeb)() so we get automatic DPCD logging

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 71c65f0a68a27..e06e8537f21e1 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1631,19 +1631,22 @@ nv50_sor_disable(struct drm_encoder *encoder,
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_crtc *nv_crtc = nouveau_crtc(nv_encoder->crtc);
+	struct nouveau_connector *nv_connector +	
nv50_outp_get_old_connector(nv_encoder, state);
 
 	nv_encoder->crtc = NULL;
 
 	if (nv_crtc) {
-		struct nvkm_i2c_aux *aux = nv_encoder->aux;
+		struct drm_dp_aux *aux = &nv_connector->aux;
 		u8 pwr;
 
-		if (aux) {
-			int ret = nvkm_rdaux(aux, DP_SET_POWER, &pwr, 1);
+		if (nv_encoder->dcb->type == DCB_OUTPUT_DP) {
+			int ret = drm_dp_dpcd_readb(aux, DP_SET_POWER, &pwr);
+
 			if (ret == 0) {
 				pwr &= ~DP_SET_POWER_MASK;
 				pwr |=  DP_SET_POWER_D3;
-				nvkm_wraux(aux, DP_SET_POWER, &pwr, 1);
+				drm_dp_dpcd_writeb(aux, DP_SET_POWER, pwr);
 			}
 		}
 
-- 
2.26.2

First some backstory here: Currently, we keep track of whether or not
we've enabled MST or not by trying to piggy-back off the MST helpers.
This means that in order to check whether MST is enabled or not, we
actually need to grab drm_dp_mst_topology_mgr.lock.

Back when I originally wrote this, I did this piggy-backing with the
intention that I'd eventually be teaching our MST helpers how to recover
when an MST device has stopped responding, which in turn would require
the MST helpers having a way of disabling MST independently of the
driver. Note that this was before I reworked locking in the MST helpers,
so at the time we were sticking random things under &mgr->lock - which
grabbing this lock was meant to protect against.

This never came to fruition because doing such a reset safely turned out
to be a lot more painful and impossible then it sounds, and also just
risks us working around issues with our MST handlers that should be
properly fixed instead. Even if it did though, simply calling
drm_dp_mst_topology_mgr_set_mst() from the MST helpers (with the
exception of when we're tearing down our MST managers, that's always OK)
wouldn't have been a bad idea, since drivers like nouveau and i915 need
to do their own book keeping immediately after disabling MST.
So-implementing that would likely require adding a hook for
helper-triggered MST disables anyway.

So, fast forward to now - we want to start adding support for all of the
miscellaneous bits of the DP protocol (for both SST and MST) we're
missing before moving on to supporting more complicated features like
supporting different BPP values on MST, DSC, etc. Since many of these
features only exist on SST and make use of DP HPD IRQs, we want to be
able to atomically check whether we're servicing an MST IRQ or SST IRQ
in nouveau_connector_hotplug(). Currently we literally don't do this at
all, and just handle any kind of possible DP IRQ we could get including
ESIs - even if MST isn't actually enabled.

This would be very complicated and difficult to fix if we need to hold
&mgr->lock while handling SST IRQs to ensure that the MST topology
state doesn't change under us. What we really want here is to do our own
tracking of whether MST is enabled or not, similar to drivers like i915,
and define our own locking order to decomplicate things and avoid
hitting locking issues in the future.

So, let's do this by refactoring our MST probing/enabling code to use
our own MST bookkeeping, along with adding a lock for protecting DP
state that needs to be checked outside of our connector probing
functions. While we're at it, we also remove a bunch of unneeded steps
we perform when probing/enabling MST:

* Enabling bits in MSTM_CTRL before calling drm_dp_mst_topology_mgr_set_mst().
  I don't think these ever actually did anything, since the nvif methods
  for enabling MST don't actually do anything DPCD related and merely
  indicate to nvkm that we've turned on MST.
* Checking the MSTM_CTRL bit is intact when checking the state of an
  enabled MST topology in nv50_mstm_detect(). I just added this to be safe
  originally, but now that we try reading the DPCD when probing DP
  connectors it shouldn't be needed as that will abort our hotplug probing
  if the device was removed well before we start checking for MST..
* All of the duplicate DPCD version checks.

This leaves us with much nicer looking code, a much more sensible
locking scheme, and an easy way of checking whether MST is enabled or
not for handling DP HPD IRQs.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv04/disp.c     |   6 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c     | 196 +++++++++-----------
 drivers/gpu/drm/nouveau/nouveau_connector.c |  14 +-
 drivers/gpu/drm/nouveau/nouveau_display.c   |   2 +-
 drivers/gpu/drm/nouveau/nouveau_display.h   |   2 +-
 drivers/gpu/drm/nouveau/nouveau_dp.c        | 134 +++++++++++--
 drivers/gpu/drm/nouveau/nouveau_encoder.h   |  33 +++-
 7 files changed, 247 insertions(+), 140 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv04/disp.c
b/drivers/gpu/drm/nouveau/dispnv04/disp.c
index 3f046b917c85c..3ee836dc5058f 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/disp.c
@@ -54,8 +54,9 @@ nv04_encoder_get_connector(struct nouveau_encoder *encoder)
 }
 
 static void
-nv04_display_fini(struct drm_device *dev, bool suspend)
+nv04_display_fini(struct drm_device *dev, bool runtime, bool suspend)
 {
+	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct nv04_display *disp = nv04_display(dev);
 	struct drm_crtc *crtc;
 
@@ -67,6 +68,9 @@ nv04_display_fini(struct drm_device *dev, bool suspend)
 	if (nv_two_heads(dev))
 		NVWriteCRTC(dev, 1, NV_PCRTC_INTR_EN_0, 0);
 
+	if (!runtime)
+		cancel_work_sync(&drm->hpd_work);
+
 	if (!suspend)
 		return;
 
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index e06e8537f21e1..8c04575fd5edb 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -880,16 +880,6 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct
drm_atomic_state *state,
 #define nv50_mstc(p) container_of((p), struct nv50_mstc, connector)
 #define nv50_msto(p) container_of((p), struct nv50_msto, encoder)
 
-struct nv50_mstm {
-	struct nouveau_encoder *outp;
-
-	struct drm_dp_mst_topology_mgr mgr;
-
-	bool modified;
-	bool disabled;
-	int links;
-};
-
 struct nv50_mstc {
 	struct nv50_mstm *mstm;
 	struct drm_dp_mst_port *port;
@@ -1418,41 +1408,51 @@ nv50_mstm = {
 	.add_connector = nv50_mstm_add_connector,
 };
 
-void
-nv50_mstm_service(struct nv50_mstm *mstm)
+bool
+nv50_mstm_service(struct nouveau_drm *drm,
+		  struct nouveau_connector *nv_connector,
+		  struct nv50_mstm *mstm)
 {
-	struct drm_dp_aux *aux = mstm ? mstm->mgr.aux : NULL;
-	bool handled = true;
-	int ret;
+	struct drm_dp_aux *aux = &nv_connector->aux;
+	bool handled = true, ret = true;
+	int rc;
 	u8 esi[8] = {};
 
-	if (!aux)
-		return;
-
 	while (handled) {
-		ret = drm_dp_dpcd_read(aux, DP_SINK_COUNT_ESI, esi, 8);
-		if (ret != 8) {
-			drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
-			return;
+		rc = drm_dp_dpcd_read(aux, DP_SINK_COUNT_ESI, esi, 8);
+		if (rc != 8) {
+			ret = false;
+			break;
 		}
 
 		drm_dp_mst_hpd_irq(&mstm->mgr, esi, &handled);
 		if (!handled)
 			break;
 
-		drm_dp_dpcd_write(aux, DP_SINK_COUNT_ESI + 1, &esi[1], 3);
+		rc = drm_dp_dpcd_write(aux, DP_SINK_COUNT_ESI + 1, &esi[1],
+				       3);
+		if (rc != 3) {
+			ret = false;
+			break;
+		}
 	}
+
+	if (!ret)
+		NV_DEBUG(drm, "Failed to handle ESI on %s: %d\n",
+			 nv_connector->base.name, rc);
+
+	return ret;
 }
 
 void
 nv50_mstm_remove(struct nv50_mstm *mstm)
 {
-	if (mstm)
-		drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
+	mstm->is_mst = false;
+	drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
 }
 
 static int
-nv50_mstm_enable(struct nv50_mstm *mstm, u8 dpcd, int state)
+nv50_mstm_enable(struct nv50_mstm *mstm, int state)
 {
 	struct nouveau_encoder *outp = mstm->outp;
 	struct {
@@ -1467,106 +1467,83 @@ nv50_mstm_enable(struct nv50_mstm *mstm, u8 dpcd, int
state)
 	};
 	struct nouveau_drm *drm = nouveau_drm(outp->base.base.dev);
 	struct nvif_object *disp = &drm->display->disp.object;
-	int ret;
-
-	if (dpcd >= 0x12) {
-		/* Even if we're enabling MST, start with disabling the
-		 * branching unit to clear any sink-side MST topology state
-		 * that wasn't set by us
-		 */
-		ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL, 0);
-		if (ret < 0)
-			return ret;
-
-		if (state) {
-			/* Now, start initializing */
-			ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL,
-						 DP_MST_EN);
-			if (ret < 0)
-				return ret;
-		}
-	}
 
 	return nvif_mthd(disp, 0, &args, sizeof(args));
 }
 
 int
-nv50_mstm_detect(struct nv50_mstm *mstm, u8 dpcd[8], int allow)
+nv50_mstm_detect(struct nouveau_encoder *outp)
 {
-	struct drm_dp_aux *aux;
+	struct nv50_mstm *mstm = outp->dp.mstm;
+	struct drm_dp_aux *aux = mstm->mgr.aux;
 	int ret;
-	bool old_state, new_state;
-	u8 mstm_ctrl;
 
-	if (!mstm)
+	if (!mstm || !mstm->can_mst)
 		return 0;
 
-	mutex_lock(&mstm->mgr.lock);
-
-	old_state = mstm->mgr.mst_state;
-	new_state = old_state;
-	aux = mstm->mgr.aux;
-
-	if (old_state) {
-		/* Just check that the MST hub is still as we expect it */
-		ret = drm_dp_dpcd_readb(aux, DP_MSTM_CTRL, &mstm_ctrl);
-		if (ret < 0 || !(mstm_ctrl & DP_MST_EN)) {
-			DRM_DEBUG_KMS("Hub gone, disabling MST topology\n");
-			new_state = false;
-		}
-	} else if (dpcd[0] >= 0x12) {
-		ret = drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &dpcd[1]);
-		if (ret < 0)
-			goto probe_error;
-
-		if (!(dpcd[1] & DP_MST_CAP))
-			dpcd[0] = 0x11;
-		else
-			new_state = allow;
-	}
-
-	if (new_state == old_state) {
-		mutex_unlock(&mstm->mgr.lock);
-		return new_state;
-	}
-
-	ret = nv50_mstm_enable(mstm, dpcd[0], new_state);
-	if (ret)
-		goto probe_error;
-
-	mutex_unlock(&mstm->mgr.lock);
+	/* Clear any leftover MST state we didn't set ourselves by first
+	 * disabling MST if it was already enabled
+	 */
+	ret = drm_dp_dpcd_writeb(aux, DP_MSTM_CTRL, 0);
+	if (ret < 0)
+		return ret;
 
-	ret = drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, new_state);
+	/* And start enabling */
+	ret = nv50_mstm_enable(mstm, true);
 	if (ret)
-		return nv50_mstm_enable(mstm, dpcd[0], 0);
+		return ret;
 
-	return new_state;
+	ret = drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, true);
+	if (ret) {
+		nv50_mstm_enable(mstm, false);
+		return ret;
+	}
 
-probe_error:
-	mutex_unlock(&mstm->mgr.lock);
-	return ret;
+	mstm->is_mst = true;
+	return 1;
 }
 
 static void
-nv50_mstm_fini(struct nv50_mstm *mstm)
+nv50_mstm_fini(struct nouveau_encoder *outp)
 {
-	if (mstm && mstm->mgr.mst_state)
+	struct nv50_mstm *mstm = outp->dp.mstm;
+
+	if (!mstm)
+		return;
+
+	/* Don't change the MST state of this connector until we've finished
+	 * resuming, since we can't safely grab hpd_irq_lock in our resume
+	 * path to protect mstm->is_mst without potentially deadlocking
+	 */
+	mutex_lock(&outp->dp.hpd_irq_lock);
+	mstm->suspended = true;
+	mutex_unlock(&outp->dp.hpd_irq_lock);
+
+	if (mstm->is_mst)
 		drm_dp_mst_topology_mgr_suspend(&mstm->mgr);
 }
 
 static void
-nv50_mstm_init(struct nv50_mstm *mstm, bool runtime)
+nv50_mstm_init(struct nouveau_encoder *outp, bool runtime)
 {
-	int ret;
+	struct nv50_mstm *mstm = outp->dp.mstm;
+	int ret = 0;
 
-	if (!mstm || !mstm->mgr.mst_state)
+	if (!mstm)
 		return;
 
-	ret = drm_dp_mst_topology_mgr_resume(&mstm->mgr, !runtime);
-	if (ret == -1) {
-		drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
-		drm_kms_helper_hotplug_event(mstm->mgr.dev);
+	if (mstm->is_mst) {
+		ret = drm_dp_mst_topology_mgr_resume(&mstm->mgr, !runtime);
+		if (ret == -1)
+			nv50_mstm_remove(mstm);
 	}
+
+	mutex_lock(&outp->dp.hpd_irq_lock);
+	mstm->suspended = false;
+	mutex_unlock(&outp->dp.hpd_irq_lock);
+
+	if (ret == -1)
+		drm_kms_helper_hotplug_event(mstm->mgr.dev);
 }
 
 static void
@@ -1774,6 +1751,10 @@ nv50_sor_destroy(struct drm_encoder *encoder)
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	nv50_mstm_del(&nv_encoder->dp.mstm);
 	drm_encoder_cleanup(encoder);
+
+	if (nv_encoder->dcb->type == DCB_OUTPUT_DP)
+		mutex_destroy(&nv_encoder->dp.hpd_irq_lock);
+
 	kfree(encoder);
 }
 
@@ -1833,6 +1814,8 @@ nv50_sor_create(struct drm_connector *connector, struct
dcb_output *dcbe)
 		struct nvkm_i2c_aux *aux  			nvkm_i2c_aux_find(i2c, dcbe->i2c_index);
 
+		mutex_init(&nv_encoder->dp.hpd_irq_lock);
+
 		if (aux) {
 			if (disp->disp->object.oclass < GF110_DISP) {
 				/* HW has no support for address-only
@@ -2531,9 +2514,9 @@ nv50_disp_func = {
  *****************************************************************************/
 
 static void
-nv50_display_fini(struct drm_device *dev, bool suspend)
+nv50_display_fini(struct drm_device *dev, bool runtime, bool suspend)
 {
-	struct nouveau_encoder *nv_encoder;
+	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct drm_encoder *encoder;
 	struct drm_plane *plane;
 
@@ -2545,11 +2528,12 @@ nv50_display_fini(struct drm_device *dev, bool suspend)
 	}
 
 	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
-		if (encoder->encoder_type != DRM_MODE_ENCODER_DPMST) {
-			nv_encoder = nouveau_encoder(encoder);
-			nv50_mstm_fini(nv_encoder->dp.mstm);
-		}
+		if (encoder->encoder_type != DRM_MODE_ENCODER_DPMST)
+			nv50_mstm_fini(nouveau_encoder(encoder));
 	}
+
+	if (!runtime)
+		cancel_work_sync(&drm->hpd_work);
 }
 
 static int
@@ -2566,7 +2550,7 @@ nv50_display_init(struct drm_device *dev, bool resume,
bool runtime)
 		if (encoder->encoder_type != DRM_MODE_ENCODER_DPMST) {
 			struct nouveau_encoder *nv_encoder  				nouveau_encoder(encoder);
-			nv50_mstm_init(nv_encoder->dp.mstm, runtime);
+			nv50_mstm_init(nv_encoder, runtime);
 		}
 	}
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 1d5696c39792a..b90591114faaf 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -1143,19 +1143,15 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 	struct nouveau_connector *nv_connector  		container_of(notify,
typeof(*nv_connector), hpd);
 	struct drm_connector *connector = &nv_connector->base;
-	struct nouveau_drm *drm = nouveau_drm(connector->dev);
+	struct drm_device *dev = connector->dev;
+	struct nouveau_drm *drm = nouveau_drm(dev);
 	const struct nvif_notify_conn_rep_v0 *rep = notify->data;
 	const char *name = connector->name;
-	struct nouveau_encoder *nv_encoder;
 	int ret;
 	bool plugged = (rep->mask != NVIF_NOTIFY_CONN_V0_UNPLUG);
 
 	if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
-		NV_DEBUG(drm, "service %s\n", name);
-		drm_dp_cec_irq(&nv_connector->aux);
-		if ((nv_encoder = find_encoder(connector, DCB_OUTPUT_DP)))
-			nv50_mstm_service(nv_encoder->dp.mstm);
-
+		nouveau_dp_irq(drm, nv_connector);
 		return NVIF_NOTIFY_KEEP;
 	}
 
@@ -1181,10 +1177,6 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 	if (!plugged)
 		drm_dp_cec_unset_edid(&nv_connector->aux);
 	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" :
"un", name);
-	if ((nv_encoder = find_encoder(connector, DCB_OUTPUT_DP))) {
-		if (!plugged)
-			nv50_mstm_remove(nv_encoder->dp.mstm);
-	}
 
 	drm_helper_hpd_irq_event(connector->dev);
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c
b/drivers/gpu/drm/nouveau/nouveau_display.c
index 5f31b11ac2e7e..13016769a194b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -569,7 +569,7 @@ nouveau_display_fini(struct drm_device *dev, bool suspend,
bool runtime)
 		cancel_work_sync(&drm->hpd_work);
 
 	drm_kms_helper_poll_disable(dev);
-	disp->fini(dev, suspend);
+	disp->fini(dev, runtime, suspend);
 }
 
 static void
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.h
b/drivers/gpu/drm/nouveau/nouveau_display.h
index 6e0d900441d69..76ba93e01aff4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.h
+++ b/drivers/gpu/drm/nouveau/nouveau_display.h
@@ -18,7 +18,7 @@ struct nouveau_display {
 	void *priv;
 	void (*dtor)(struct drm_device *);
 	int  (*init)(struct drm_device *, bool resume, bool runtime);
-	void (*fini)(struct drm_device *, bool suspend);
+	void (*fini)(struct drm_device *, bool suspend, bool runtime);
 
 	struct nvif_disp disp;
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 4030806e3522b..d701f09aea645 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -36,19 +36,89 @@ MODULE_PARM_DESC(mst, "Enable DisplayPort multi-stream
(default: enabled)");
 static int nouveau_mst = 1;
 module_param_named(mst, nouveau_mst, int, 0400);
 
+static enum drm_connector_status
+nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
+		      struct nouveau_encoder *outp)
+{
+	struct drm_dp_aux *aux = &nv_connector->aux;
+	struct nv50_mstm *mstm = NULL;
+	int ret;
+	u8 *dpcd = outp->dp.dpcd;
+	u8 tmp;
+
+	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
+	if (ret == DP_RECEIVER_CAP_SIZE && dpcd[DP_DPCD_REV]) {
+		ret = drm_dp_read_desc(aux, &outp->dp.desc,
+				       drm_dp_is_branch(dpcd));
+		if (ret < 0)
+			return connector_status_disconnected;
+	} else {
+		return connector_status_disconnected;
+	}
+
+	if (nouveau_mst)
+		mstm = outp->dp.mstm;
+
+	if (mstm) {
+		if (dpcd[DP_DPCD_REV] >= DP_DPCD_REV_12) {
+			ret = drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &tmp);
+			if (ret < 0)
+				return connector_status_disconnected;
+
+			mstm->can_mst = !!(tmp & DP_MST_CAP);
+		} else {
+			mstm->can_mst = false;
+		}
+	}
+
+	return connector_status_connected;
+}
+
 int
 nouveau_dp_detect(struct nouveau_connector *nv_connector,
 		  struct nouveau_encoder *nv_encoder)
 {
 	struct drm_device *dev = nv_encoder->base.base.dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
-	struct drm_dp_aux *aux = &nv_connector->aux;
-	u8 dpcd[DP_RECEIVER_CAP_SIZE];
-	int ret;
+	struct drm_connector *connector = &nv_connector->base;
+	struct nv50_mstm *mstm = nv_encoder->dp.mstm;
+	enum drm_connector_status status;
+	u8 *dpcd = nv_encoder->dp.dpcd;
+	int ret = NOUVEAU_DP_NONE;
+
+	/* If we've already read the DPCD on an eDP device, we don't need to
+	 * reread it as it won't change
+	 */
+	if (connector->connector_type == DRM_MODE_CONNECTOR_eDP &&
+	    dpcd[DP_DPCD_REV] != 0)
+		return NOUVEAU_DP_SST;
 
-	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
-	if (ret != sizeof(dpcd))
-		return ret;
+	mutex_lock(&nv_encoder->dp.hpd_irq_lock);
+	if (mstm) {
+		/* If we're not ready to handle MST state changes yet, just
+		 * report the last status of the connector. We'll reprobe it
+		 * once we've resumed.
+		 */
+		if (mstm->suspended) {
+			if (mstm->is_mst)
+				ret = NOUVEAU_DP_MST;
+			else if (connector->status =+				 connector_status_connected)
+				ret = NOUVEAU_DP_SST;
+
+			goto out;
+		}
+	}
+
+	status = nouveau_dp_probe_dpcd(nv_connector, nv_encoder);
+	if (status == connector_status_disconnected)
+		goto out;
+
+	/* If we're in MST mode, we're done here */
+	if (mstm && mstm->can_mst && mstm->is_mst) {
+		ret = NOUVEAU_DP_MST;
+		goto out;
+	}
 
 	nv_encoder->dp.link_bw = 27000 * dpcd[DP_MAX_LINK_RATE];
 	nv_encoder->dp.link_nr @@ -69,22 +139,52 @@ nouveau_dp_detect(struct
nouveau_connector *nv_connector,
 	NV_DEBUG(drm, "maximum: %dx%d\n",
 		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
 
-	ret = drm_dp_read_desc(&nv_connector->aux, &nv_encoder->dp.desc,
-			       drm_dp_is_branch(dpcd));
-	if (ret) {
-		NV_ERROR(drm, "Failed to read DP descriptor on %s: %d\n",
-			 nv_connector->base.name, ret);
-		return ret;
+	if (mstm && mstm->can_mst) {
+		ret = nv50_mstm_detect(nv_encoder);
+		if (ret == 1) {
+			ret = NOUVEAU_DP_MST;
+			goto out;
+		} else if (ret != 0) {
+			goto out;
+		}
 	}
+	ret = NOUVEAU_DP_SST;
 
-	ret = nv50_mstm_detect(nv_encoder->dp.mstm, dpcd, nouveau_mst);
-	if (ret == 1)
-		return NOUVEAU_DP_MST;
-	if (ret == 0)
-		return NOUVEAU_DP_SST;
+out:
+	if (mstm && !mstm->suspended && ret != NOUVEAU_DP_MST)
+		nv50_mstm_remove(mstm);
+
+	mutex_unlock(&nv_encoder->dp.hpd_irq_lock);
 	return ret;
 }
 
+
+
+void nouveau_dp_irq(struct nouveau_drm *drm,
+		    struct nouveau_connector *nv_connector)
+{
+	struct drm_connector *connector = &nv_connector->base;
+	struct nouveau_encoder *outp = find_encoder(connector, DCB_OUTPUT_DP);
+	struct nv50_mstm *mstm;
+
+	if (!outp)
+		return;
+
+	mstm = outp->dp.mstm;
+	NV_DEBUG(drm, "service %s\n", connector->name);
+
+	mutex_lock(&outp->dp.hpd_irq_lock);
+
+	if (mstm && mstm->is_mst) {
+		if (!nv50_mstm_service(drm, nv_connector, mstm))
+			schedule_work(&drm->hpd_work);
+	} else {
+		drm_dp_cec_irq(&nv_connector->aux);
+	}
+
+	mutex_unlock(&outp->dp.hpd_irq_lock);
+}
+
 /* TODO:
  * - Use the minimum possible BPC here, once we add support for the max bpc
  *   property.
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h
b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index b0e1dad2367d6..eef4643f5f982 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -65,6 +65,13 @@ struct nouveau_encoder {
 			struct nv50_mstm *mstm;
 			int link_nr;
 			int link_bw;
+
+			/* Protects DP state that needs to be accessed outside
+			 * connector reprobing contexts
+			 */
+			struct mutex hpd_irq_lock;
+
+			u8 dpcd[DP_RECEIVER_CAP_SIZE];
 			struct drm_dp_desc desc;
 		} dp;
 	};
@@ -79,6 +86,21 @@ struct nouveau_encoder {
 		       struct nv50_head_atom *, u8 proto, u8 depth);
 };
 
+struct nv50_mstm {
+	struct nouveau_encoder *outp;
+
+	struct drm_dp_mst_topology_mgr mgr;
+
+	/* Protected under nouveau_encoder->dp.hpd_irq_lock */
+	bool can_mst;
+	bool is_mst;
+	bool suspended;
+
+	bool modified;
+	bool disabled;
+	int links;
+};
+
 struct nouveau_encoder *
 find_encoder(struct drm_connector *connector, int type);
 
@@ -102,11 +124,14 @@ get_slave_funcs(struct drm_encoder *enc)
 
 /* nouveau_dp.c */
 enum nouveau_dp_status {
+	NOUVEAU_DP_NONE,
 	NOUVEAU_DP_SST,
 	NOUVEAU_DP_MST,
 };
 
 int nouveau_dp_detect(struct nouveau_connector *, struct nouveau_encoder *);
+void nouveau_dp_irq(struct nouveau_drm *drm,
+		    struct nouveau_connector *nv_connector);
 enum drm_mode_status nv50_dp_mode_valid(struct drm_connector *,
 					struct nouveau_encoder *,
 					const struct drm_display_mode *,
@@ -119,7 +144,9 @@ struct nouveau_connector *
 nv50_outp_get_old_connector(struct nouveau_encoder *outp,
 			    struct drm_atomic_state *state);
 
-int nv50_mstm_detect(struct nv50_mstm *, u8 dpcd[8], int allow);
-void nv50_mstm_remove(struct nv50_mstm *);
-void nv50_mstm_service(struct nv50_mstm *);
+int nv50_mstm_detect(struct nouveau_encoder *encoder);
+void nv50_mstm_remove(struct nv50_mstm *mstm);
+bool nv50_mstm_service(struct nouveau_drm *drm,
+		       struct nouveau_connector *nv_connector,
+		       struct nv50_mstm *mstm);
 #endif /* __NOUVEAU_ENCODER_H__ */
-- 
2.26.2

Just a tiny drive-by cleanup, we can consolidate i915's code for
checking for MST support into a helper to be shared across drivers.

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 18 ++----------------
 include/drm/drm_dp_mst_helper.h         | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index 79c27f91f42c0..1e29d3a012856 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4699,20 +4699,6 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 	return true;
 }
 
-static bool
-intel_dp_sink_can_mst(struct intel_dp *intel_dp)
-{
-	u8 mstm_cap;
-
-	if (intel_dp->dpcd[DP_DPCD_REV] < 0x12)
-		return false;
-
-	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_MSTM_CAP, &mstm_cap) != 1)
-		return false;
-
-	return mstm_cap & DP_MST_CAP;
-}
-
 static bool
 intel_dp_can_mst(struct intel_dp *intel_dp)
 {
@@ -4720,7 +4706,7 @@ intel_dp_can_mst(struct intel_dp *intel_dp)
 
 	return i915->params.enable_dp_mst &&
 		intel_dp->can_mst &&
-		intel_dp_sink_can_mst(intel_dp);
+		drm_dp_has_mst(&intel_dp->aux, intel_dp->dpcd);
 }
 
 static void
@@ -4729,7 +4715,7 @@ intel_dp_configure_mst(struct intel_dp *intel_dp)
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	struct intel_encoder *encoder  		&dp_to_dig_port(intel_dp)->base;
-	bool sink_can_mst = intel_dp_sink_can_mst(intel_dp);
+	bool sink_can_mst = drm_dp_has_mst(&intel_dp->aux, intel_dp->dpcd);
 
 	drm_dbg_kms(&i915->drm,
 		    "[ENCODER:%d:%s] MST support: port: %s, sink: %s, modparam:
%s\n",
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 8b9eb4db3381c..2d8983a713e8c 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -911,4 +911,26 @@ __drm_dp_mst_state_iter_get(struct drm_atomic_state *state,
 	for ((__i) = 0; (__i) < (__state)->num_private_objs; (__i)++) \
 		for_each_if(__drm_dp_mst_state_iter_get((__state), &(mgr), NULL,
&(new_state), (__i)))
 
+/**
+ * drm_dp_has_mst() - check whether or not a sink supports MST
+ * @aux: The DP AUX channel to use
+ * @dpcd: A cached copy of the DPCD capabilities for this sink
+ *
+ * Returns: %True if the sink supports MST, %false otherwise
+ */
+static inline bool
+drm_dp_has_mst(struct drm_dp_aux *aux,
+	       const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 mstm_cap;
+
+	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
+		return false;
+
+	if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
+		return false;
+
+	return !!(mstm_cap & DP_MST_CAP);
+}
+
 #endif
-- 
2.26.2

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index d701f09aea645..bb85d81c25244 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -44,7 +44,6 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 	struct nv50_mstm *mstm = NULL;
 	int ret;
 	u8 *dpcd = outp->dp.dpcd;
-	u8 tmp;
 
 	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
 	if (ret == DP_RECEIVER_CAP_SIZE && dpcd[DP_DPCD_REV]) {
@@ -56,19 +55,10 @@ nouveau_dp_probe_dpcd(struct nouveau_connector
*nv_connector,
 		return connector_status_disconnected;
 	}
 
-	if (nouveau_mst)
+	if (nouveau_mst) {
 		mstm = outp->dp.mstm;
-
-	if (mstm) {
-		if (dpcd[DP_DPCD_REV] >= DP_DPCD_REV_12) {
-			ret = drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &tmp);
-			if (ret < 0)
-				return connector_status_disconnected;
-
-			mstm->can_mst = !!(tmp & DP_MST_CAP);
-		} else {
-			mstm->can_mst = false;
-		}
+		if (mstm)
+			mstm->can_mst = drm_dp_has_mst(aux, dpcd);
 	}
 
 	return connector_status_connected;
-- 
2.26.2

For whatever reason we currently unset the EDID for DP CEC support when
responding to the connector being unplugged, instead of just doing it in
nouveau_connector_detect() where we set the CEC EDID. This isn't really
needed and could even potentially cause us to forget to unset the EDID
if the connector is removed without a corresponding hpd event, so let's
fix that.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
index b90591114faaf..4a29f691c08e4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -633,10 +633,11 @@ nouveau_connector_detect(struct drm_connector *connector,
bool force)
 			conn_status = connector_status_connected;
 			goto out;
 		}
-
 	}
 
  out:
+	if (!nv_connector->edid)
+		drm_dp_cec_unset_edid(&nv_connector->aux);
 
 	pm_runtime_mark_last_busy(dev->dev);
 	pm_runtime_put_autosuspend(dev->dev);
@@ -1174,8 +1175,6 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 		return NVIF_NOTIFY_DROP;
 	}
 
-	if (!plugged)
-		drm_dp_cec_unset_edid(&nv_connector->aux);
 	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" :
"un", name);
 
 	drm_helper_hpd_irq_event(connector->dev);
-- 
2.26.2

Currently we perform both short IRQ handling for DP, and connector
reprobing in the HPD IRQ handler. However since we need to grab
connection_mutex in order to reprobe a connector, in theory we could
accidentally block ourselves from handling any short IRQs until after a
modeset completes if a connector hotplug happens to occur in parallel
with a modeset.

I haven't seen this actually happen yet, but since we're cleaning up
nouveau's hotplug handling code anyway and we already have a hpd worker,
we can simply fix this by only relying on the HPD worker to actually
reprobe connectors when we receive a HPD IRQ. We also add a mask to
nouveau_drm to keep track of which connectors are waiting to be reprobed
in response to an HPD IRQ.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 42 +++++--------
 drivers/gpu/drm/nouveau/nouveau_connector.h |  1 +
 drivers/gpu/drm/nouveau/nouveau_display.c   | 70 ++++++++++++++++++---
 drivers/gpu/drm/nouveau/nouveau_display.h   |  1 +
 drivers/gpu/drm/nouveau/nouveau_dp.c        |  2 +-
 drivers/gpu/drm/nouveau/nouveau_drm.c       |  4 +-
 drivers/gpu/drm/nouveau/nouveau_drv.h       |  2 +
 7 files changed, 86 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 4a29f691c08e4..637e91594fbe8 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -1138,6 +1138,20 @@ nouveau_connector_funcs_lvds = {
 	.early_unregister = nouveau_connector_early_unregister,
 };
 
+void
+nouveau_connector_hpd(struct drm_connector *connector)
+{
+	struct nouveau_drm *drm = nouveau_drm(connector->dev);
+	u32 mask = drm_connector_mask(connector);
+
+	mutex_lock(&drm->hpd_lock);
+	if (!(drm->hpd_pending & mask)) {
+		drm->hpd_pending |= mask;
+		schedule_work(&drm->hpd_work);
+	}
+	mutex_unlock(&drm->hpd_lock);
+}
+
 static int
 nouveau_connector_hotplug(struct nvif_notify *notify)
 {
@@ -1147,8 +1161,6 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 	struct drm_device *dev = connector->dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	const struct nvif_notify_conn_rep_v0 *rep = notify->data;
-	const char *name = connector->name;
-	int ret;
 	bool plugged = (rep->mask != NVIF_NOTIFY_CONN_V0_UNPLUG);
 
 	if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
@@ -1156,31 +1168,9 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 		return NVIF_NOTIFY_KEEP;
 	}
 
-	ret = pm_runtime_get(drm->dev->dev);
-	if (ret == 0) {
-		/* We can't block here if there's a pending PM request
-		 * running, as we'll deadlock nouveau_display_fini() when it
-		 * calls nvif_put() on our nvif_notify struct. So, simply
-		 * defer the hotplug event until the device finishes resuming
-		 */
-		NV_DEBUG(drm, "Deferring HPD on %s until runtime resume\n",
-			 name);
-		schedule_work(&drm->hpd_work);
-
-		pm_runtime_put_noidle(drm->dev->dev);
-		return NVIF_NOTIFY_KEEP;
-	} else if (ret != 1 && ret != -EACCES) {
-		NV_WARN(drm, "HPD on %s dropped due to RPM failure: %d\n",
-			name, ret);
-		return NVIF_NOTIFY_DROP;
-	}
-
-	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" :
"un", name);
-
-	drm_helper_hpd_irq_event(connector->dev);
+	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" :
"un", connector->name);
+	nouveau_connector_hpd(connector);
 
-	pm_runtime_mark_last_busy(drm->dev->dev);
-	pm_runtime_put_autosuspend(drm->dev->dev);
 	return NVIF_NOTIFY_KEEP;
 }
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.h
b/drivers/gpu/drm/nouveau/nouveau_connector.h
index d6de5cb8e2238..d0b859c4a80ea 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.h
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.h
@@ -187,6 +187,7 @@ nouveau_crtc_connector_get(struct nouveau_crtc *nv_crtc)
 
 struct drm_connector *
 nouveau_connector_create(struct drm_device *, const struct dcb_output *);
+void nouveau_connector_hpd(struct drm_connector *connector);
 
 extern int nouveau_tv_disable;
 extern int nouveau_ignorelid;
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c
b/drivers/gpu/drm/nouveau/nouveau_display.c
index 13016769a194b..bceb48a2dfca6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -457,16 +457,70 @@ static struct nouveau_drm_prop_enum_list dither_depth[] =
{
 	}                                                                      \
 } while(0)
 
+void
+nouveau_display_hpd_resume(struct drm_device *dev)
+{
+	struct nouveau_drm *drm = nouveau_drm(dev);
+
+	mutex_lock(&drm->hpd_lock);
+	drm->hpd_pending = ~0;
+	mutex_unlock(&drm->hpd_lock);
+
+	schedule_work(&drm->hpd_work);
+}
+
 static void
 nouveau_display_hpd_work(struct work_struct *work)
 {
 	struct nouveau_drm *drm = container_of(work, typeof(*drm), hpd_work);
+	struct drm_device *dev = drm->dev;
+	struct drm_connector *connector;
+	struct drm_connector_list_iter conn_iter;
+	u32 pending;
+	bool changed = false;
+
+	pm_runtime_get_sync(dev->dev);
 
-	pm_runtime_get_sync(drm->dev->dev);
+	mutex_lock(&drm->hpd_lock);
+	pending = drm->hpd_pending;
+	drm->hpd_pending = 0;
+	mutex_unlock(&drm->hpd_lock);
 
-	drm_helper_hpd_irq_event(drm->dev);
+	/* Nothing to do, exit early without updating the last busy counter */
+	if (!pending)
+		goto noop;
+
+	mutex_lock(&dev->mode_config.mutex);
+	drm_connector_list_iter_begin(dev, &conn_iter);
+
+	nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
+		enum drm_connector_status old_status = connector->status;
+		u64 old_epoch_counter = connector->epoch_counter;
+
+		if (!(pending & drm_connector_mask(connector)))
+			continue;
+
+		connector->status = drm_helper_probe_detect(connector, NULL,
+							    false);
+		if (old_epoch_counter == connector->epoch_counter)
+			continue;
+
+		changed = true;
+		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s (epoch
counter %llu->%llu)\n",
+			    connector->base.id, connector->name,
+			    drm_get_connector_status_name(old_status),
+			    drm_get_connector_status_name(connector->status),
+			    old_epoch_counter, connector->epoch_counter);
+	}
+
+	drm_connector_list_iter_end(&conn_iter);
+	mutex_unlock(&dev->mode_config.mutex);
+
+	if (changed)
+		drm_kms_helper_hotplug_event(dev);
 
 	pm_runtime_mark_last_busy(drm->dev->dev);
+noop:
 	pm_runtime_put_sync(drm->dev->dev);
 }
 
@@ -490,12 +544,11 @@ nouveau_display_acpi_ntfy(struct notifier_block *nb,
unsigned long val,
 				 */
 				pm_runtime_put_autosuspend(drm->dev->dev);
 			} else if (ret == 0) {
-				/* This may be the only indication we receive
-				 * of a connector hotplug on a runtime
-				 * suspended GPU, schedule hpd_work to check.
+				/* We've started resuming the GPU already, so
+				 * it will handle scheduling a full reprobe
+				 * itself
 				 */
 				NV_DEBUG(drm, "ACPI requested connector reprobe\n");
-				schedule_work(&drm->hpd_work);
 				pm_runtime_put_noidle(drm->dev->dev);
 			} else {
 				NV_WARN(drm, "Dropped ACPI reprobe event due to RPM error: %d\n",
@@ -686,6 +739,7 @@ nouveau_display_create(struct drm_device *dev)
 	}
 
 	INIT_WORK(&drm->hpd_work, nouveau_display_hpd_work);
+	mutex_init(&drm->hpd_lock);
 #ifdef CONFIG_ACPI
 	drm->acpi_nb.notifier_call = nouveau_display_acpi_ntfy;
 	register_acpi_notifier(&drm->acpi_nb);
@@ -705,9 +759,10 @@ void
 nouveau_display_destroy(struct drm_device *dev)
 {
 	struct nouveau_display *disp = nouveau_display(dev);
+	struct nouveau_drm *drm = nouveau_drm(dev);
 
 #ifdef CONFIG_ACPI
-	unregister_acpi_notifier(&nouveau_drm(dev)->acpi_nb);
+	unregister_acpi_notifier(&drm->acpi_nb);
 #endif
 
 	drm_kms_helper_poll_fini(dev);
@@ -719,6 +774,7 @@ nouveau_display_destroy(struct drm_device *dev)
 	nvif_disp_dtor(&disp->disp);
 
 	nouveau_drm(dev)->display = NULL;
+	mutex_destroy(&drm->hpd_lock);
 	kfree(disp);
 }
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.h
b/drivers/gpu/drm/nouveau/nouveau_display.h
index 76ba93e01aff4..616c434270594 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.h
+++ b/drivers/gpu/drm/nouveau/nouveau_display.h
@@ -45,6 +45,7 @@ nouveau_display(struct drm_device *dev)
 int  nouveau_display_create(struct drm_device *dev);
 void nouveau_display_destroy(struct drm_device *dev);
 int  nouveau_display_init(struct drm_device *dev, bool resume, bool runtime);
+void nouveau_display_hpd_resume(struct drm_device *dev);
 void nouveau_display_fini(struct drm_device *dev, bool suspend, bool runtime);
 int  nouveau_display_suspend(struct drm_device *dev, bool runtime);
 void nouveau_display_resume(struct drm_device *dev, bool runtime);
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index bb85d81c25244..c6a04d0ac99d1 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -167,7 +167,7 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 
 	if (mstm && mstm->is_mst) {
 		if (!nv50_mstm_service(drm, nv_connector, mstm))
-			schedule_work(&drm->hpd_work);
+			nouveau_connector_hpd(connector);
 	} else {
 		drm_dp_cec_irq(&nv_connector->aux);
 	}
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 22d246acc5e52..42fc5c813a9bb 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -953,7 +953,7 @@ nouveau_pmops_resume(struct device *dev)
 	ret = nouveau_do_resume(drm_dev, false);
 
 	/* Monitors may have been connected / disconnected during suspend */
-	schedule_work(&nouveau_drm(drm_dev)->hpd_work);
+	nouveau_display_hpd_resume(drm_dev);
 
 	return ret;
 }
@@ -1036,7 +1036,7 @@ nouveau_pmops_runtime_resume(struct device *dev)
 	drm_dev->switch_power_state = DRM_SWITCH_POWER_ON;
 
 	/* Monitors may have been connected / disconnected during suspend */
-	schedule_work(&nouveau_drm(drm_dev)->hpd_work);
+	nouveau_display_hpd_resume(drm_dev);
 
 	return ret;
 }
diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h
b/drivers/gpu/drm/nouveau/nouveau_drv.h
index f63ac72aa556f..73ebf5fba2fcd 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -198,6 +198,8 @@ struct nouveau_drm {
 	struct nvbios vbios;
 	struct nouveau_display *display;
 	struct work_struct hpd_work;
+	struct mutex hpd_lock;
+	u32 hpd_pending;
 	struct work_struct fbcon_work;
 	int fbcon_new_state;
 #ifdef CONFIG_ACPI
-- 
2.26.2

We're going to be doing the same probing process in nouveau for
determining downstream DP port capabilities, so let's deduplicate the
work by moving i915's code for handling this into a shared helper:
drm_dp_downstream_read_info().

Note that when we do this, we also do make some functional changes while
we're at it:
* We always clear the downstream port info before trying to read it,
  just to make things easier for the caller
* We skip reading downstream port info if the DPCD indicates that we
  don't support downstream port info
* We only read as many bytes as needed for the reported number of
  downstream ports, no sense in reading the whole thing every time

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/drm_dp_helper.c         | 32 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c | 14 ++---------
 include/drm/drm_dp_helper.h             |  3 +++
 3 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 4c21cf69dad5a..9703b33599c3b 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -423,6 +423,38 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
 }
 EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
 
+/**
+ * drm_dp_downstream_read_info() - read DPCD downstream port info if available
+ * @aux: DisplayPort AUX channel
+ * @dpcd: A cached copy of the port's DPCD
+ * @downstream_ports: buffer to store the downstream port info in
+ *
+ * Returns: 0 if either the downstream port info was read successfully or
+ * there was no downstream info to read, or a negative error code otherwise.
+ */
+int drm_dp_downstream_read_info(struct drm_dp_aux *aux,
+				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS])
+{
+	int ret;
+	u8 len;
+
+	memset(downstream_ports, 0, DP_MAX_DOWNSTREAM_PORTS);
+
+	/* No downstream info to read */
+	if (!drm_dp_is_branch(dpcd) ||
+	    dpcd[DP_DPCD_REV] < DP_DPCD_REV_10 ||
+	    !(dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT))
+		return 0;
+
+	len = (dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_PORT_COUNT_MASK) * 4;
+	ret = drm_dp_dpcd_read(aux, DP_DOWNSTREAM_PORT_0, downstream_ports,
+			       len);
+
+	return ret == len ? 0 : -EIO;
+}
+EXPORT_SYMBOL(drm_dp_downstream_read_info);
+
 /**
  * drm_dp_downstream_max_clock() - extract branch device max
  *                                 pixel rate for legacy VGA
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index 1e29d3a012856..984e49194ca31 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4685,18 +4685,8 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 			return false;
 	}
 
-	if (!drm_dp_is_branch(intel_dp->dpcd))
-		return true; /* native DP sink */
-
-	if (intel_dp->dpcd[DP_DPCD_REV] == 0x10)
-		return true; /* no per-port downstream info */
-
-	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DOWNSTREAM_PORT_0,
-			     intel_dp->downstream_ports,
-			     DP_MAX_DOWNSTREAM_PORTS) < 0)
-		return false; /* downstream port status fetch failed */
-
-	return true;
+	return drm_dp_downstream_read_info(&intel_dp->aux, intel_dp->dpcd,
+					   intel_dp->downstream_ports) == 0;
 }
 
 static bool
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 5c28199248626..1349f16564ace 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1613,6 +1613,9 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
 				    u8 real_edid_checksum);
 
+int drm_dp_downstream_read_info(struct drm_dp_aux *aux,
+				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS]);
 int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 				const u8 port_cap[4]);
 int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
-- 
2.26.2

This adds support for querying the maximum clock rate of a downstream
port on a DisplayPort connection. Generally, downstream ports refer to
active dongles which can have their own pixel clock limits.

Note as well, we also start marking the connector as disconnected if we
can't read the DPCD, since we wouldn't be able to do anything without
DPCD access anyway.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c   |  3 +++
 drivers/gpu/drm/nouveau/nouveau_dp.c      | 15 +++++++++++----
 drivers/gpu/drm/nouveau/nouveau_encoder.h |  1 +
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 8c04575fd5edb..df64a24538671 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1259,7 +1259,10 @@ nv50_mstc_detect(struct drm_connector *connector,
 
 	ret = drm_dp_mst_detect_port(connector, ctx, mstc->port->mgr,
 				     mstc->port);
+	if (ret != connector_status_connected)
+		goto out;
 
+out:
 	pm_runtime_mark_last_busy(connector->dev->dev);
 	pm_runtime_put_autosuspend(connector->dev->dev);
 	return ret;
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index c6a04d0ac99d1..f6950a62138ca 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -61,6 +61,11 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 			mstm->can_mst = drm_dp_has_mst(aux, dpcd);
 	}
 
+	ret = drm_dp_downstream_read_info(aux, dpcd,
+					  outp->dp.downstream_ports);
+	if (ret < 0)
+		return connector_status_disconnected;
+
 	return connector_status_connected;
 }
 
@@ -178,8 +183,6 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 /* TODO:
  * - Use the minimum possible BPC here, once we add support for the max bpc
  *   property.
- * - Validate the mode against downstream port caps (see
- *   drm_dp_downstream_max_clock())
  * - Validate against the DP caps advertised by the GPU (we don't check
these
  *   yet)
  */
@@ -190,15 +193,19 @@ nv50_dp_mode_valid(struct drm_connector *connector,
 		   unsigned *out_clock)
 {
 	const unsigned min_clock = 25000;
-	unsigned max_clock, clock;
+	unsigned max_clock, ds_clock, clock;
 	enum drm_mode_status ret;
 
 	if (mode->flags & DRM_MODE_FLAG_INTERLACE &&
!outp->caps.dp_interlace)
 		return MODE_NO_INTERLACE;
 
 	max_clock = outp->dp.link_nr * outp->dp.link_bw;
-	clock = mode->clock * (connector->display_info.bpc * 3) / 10;
+	ds_clock = drm_dp_downstream_max_clock(outp->dp.dpcd,
+					       outp->dp.downstream_ports);
+	if (ds_clock)
+		max_clock = min(max_clock, ds_clock);
 
+	clock = mode->clock * (connector->display_info.bpc * 3) / 10;
 	ret = nouveau_conn_mode_clock_valid(mode, min_clock, max_clock,
 					    &clock);
 	if (out_clock)
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h
b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index eef4643f5f982..c1924a4529a7b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -72,6 +72,7 @@ struct nouveau_encoder {
 			struct mutex hpd_irq_lock;
 
 			u8 dpcd[DP_RECEIVER_CAP_SIZE];
+			u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
 			struct drm_dp_desc desc;
 		} dp;
 	};
-- 
2.26.2

Since other drivers are also going to need to be aware of the sink count
in order to do proper dongle detection, we might as well steal i915's
DP_SINK_COUNT helpers and move them into DRM helpers so that other
dirvers can use them as well.

Note that this also starts using intel_dp_has_sink_count() in
intel_dp_detect_dpcd(), which is a functional change.

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/drm_dp_helper.c         | 22 ++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c | 21 ++++++++++++---------
 include/drm/drm_dp_helper.h             |  8 +++++++-
 3 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 9703b33599c3b..05bb47e589731 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -700,6 +700,28 @@ void drm_dp_set_subconnector_property(struct drm_connector
*connector,
 }
 EXPORT_SYMBOL(drm_dp_set_subconnector_property);
 
+/**
+ * drm_dp_has_sink_count() - Check whether a given connector has a valid sink
+ * count
+ * @connector: The DRM connector to check
+ * @dpcd: A cached copy of the connector's DPCD RX capabilities
+ * @desc: A cached copy of the connector's DP descriptor
+ *
+ * Returns: %True if the (e)DP connector has a valid sink count that should
+ * be probed, %false otherwise.
+ */
+bool drm_dp_has_sink_count(struct drm_connector *connector,
+			   const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+			   const struct drm_dp_desc *desc)
+{
+	/* Some eDP panels don't set a valid value for the sink count */
+	return connector->connector_type != DRM_MODE_CONNECTOR_eDP &&
+		dpcd[DP_DPCD_REV] >= DP_DPCD_REV_11 &&
+		dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT &&
+		!drm_dp_has_quirk(desc, 0, DP_DPCD_QUIRK_NO_SINK_COUNT);
+}
+EXPORT_SYMBOL(drm_dp_has_sink_count);
+
 /*
  * I2C-over-AUX implementation
  */
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index 984e49194ca31..35a4779a442e2 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4634,6 +4634,16 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
 	return true;
 }
 
+static bool
+intel_dp_has_sink_count(struct intel_dp *intel_dp)
+{
+	if (!intel_dp->attached_connector)
+		return false;
+
+	return drm_dp_has_sink_count(&intel_dp->attached_connector->base,
+				     intel_dp->dpcd,
+				     &intel_dp->desc);
+}
 
 static bool
 intel_dp_get_dpcd(struct intel_dp *intel_dp)
@@ -4653,13 +4663,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 		intel_dp_set_common_rates(intel_dp);
 	}
 
-	/*
-	 * Some eDP panels do not set a valid value for sink count, that is why
-	 * it don't care about read it here and in intel_edp_init_dpcd().
-	 */
-	if (!intel_dp_is_edp(intel_dp) &&
-	    !drm_dp_has_quirk(&intel_dp->desc, 0,
-			      DP_DPCD_QUIRK_NO_SINK_COUNT)) {
+	if (intel_dp_has_sink_count(intel_dp)) {
 		u8 count;
 		ssize_t r;
 
@@ -5939,9 +5943,8 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
 		return connector_status_connected;
 
 	/* If we're HPD-aware, SINK_COUNT changes dynamically */
-	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
+	if (intel_dp_has_sink_count(intel_dp) &&
 	    intel_dp->downstream_ports[0] & DP_DS_PORT_HPD) {
-
 		return intel_dp->sink_count ?
 		connector_status_connected : connector_status_disconnected;
 	}
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 1349f16564ace..a1413a531eaf4 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1631,6 +1631,11 @@ void drm_dp_set_subconnector_property(struct
drm_connector *connector,
 				      const u8 *dpcd,
 				      const u8 port_cap[4]);
 
+struct drm_dp_desc;
+bool drm_dp_has_sink_count(struct drm_connector *connector,
+			   const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+			   const struct drm_dp_desc *desc);
+
 void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
 void drm_dp_aux_init(struct drm_dp_aux *aux);
 int drm_dp_aux_register(struct drm_dp_aux *aux);
@@ -1689,7 +1694,8 @@ enum drm_dp_quirk {
 	 * @DP_DPCD_QUIRK_NO_SINK_COUNT:
 	 *
 	 * The device does not set SINK_COUNT to a non-zero value.
-	 * The driver should ignore SINK_COUNT during detection.
+	 * The driver should ignore SINK_COUNT during detection. Note that
+	 * drm_dp_has_sink_count() automatically checks for this quirk.
 	 */
 	DP_DPCD_QUIRK_NO_SINK_COUNT,
 	/**
-- 
2.26.2

And of course, we'll also need to read the sink count from other drivers
as well if we're checking whether or not it's supported. So, let's
extract the code for this into another helper.

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/drm_dp_helper.c         | 20 ++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c | 17 +++++------------
 include/drm/drm_dp_helper.h             |  1 +
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 05bb47e589731..0ff2959c8f8e8 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -722,6 +722,26 @@ bool drm_dp_has_sink_count(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_dp_has_sink_count);
 
+/**
+ * drm_dp_get_sink_count() - Retrieve the sink count for a given sink
+ * @aux: The DP AUX channel to use
+ *
+ * Returns: The current sink count reported by @aux, or a negative error code
+ * otherwise.
+ */
+int drm_dp_get_sink_count(struct drm_dp_aux *aux)
+{
+	u8 count;
+	int ret;
+
+	ret = drm_dp_dpcd_readb(aux, DP_SINK_COUNT, &count);
+	if (ret < 1)
+		return -EIO;
+
+	return DP_GET_SINK_COUNT(count);
+}
+EXPORT_SYMBOL(drm_dp_get_sink_count);
+
 /*
  * I2C-over-AUX implementation
  */
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index 35a4779a442e2..e343965a483df 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4648,6 +4648,8 @@ intel_dp_has_sink_count(struct intel_dp *intel_dp)
 static bool
 intel_dp_get_dpcd(struct intel_dp *intel_dp)
 {
+	int ret;
+
 	if (!intel_dp_read_dpcd(intel_dp))
 		return false;
 
@@ -4664,20 +4666,10 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 	}
 
 	if (intel_dp_has_sink_count(intel_dp)) {
-		u8 count;
-		ssize_t r;
-
-		r = drm_dp_dpcd_readb(&intel_dp->aux, DP_SINK_COUNT, &count);
-		if (r < 1)
+		ret = drm_dp_get_sink_count(&intel_dp->aux);
+		if (ret < 0)
 			return false;
 
-		/*
-		 * Sink count can change between short pulse hpd hence
-		 * a member variable in intel_dp will track any changes
-		 * between short pulse interrupts.
-		 */
-		intel_dp->sink_count = DP_GET_SINK_COUNT(count);
-
 		/*
 		 * SINK_COUNT == 0 and DOWNSTREAM_PORT_PRESENT == 1 implies that
 		 * a dongle is present but no display. Unless we require to know
@@ -4685,6 +4677,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 		 * downstream port information. So, an early return here saves
 		 * time from performing other operations which are not required.
 		 */
+		intel_dp->sink_count = ret;
 		if (!intel_dp->sink_count)
 			return false;
 	}
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index a1413a531eaf4..0c141fc81aaa8 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1635,6 +1635,7 @@ struct drm_dp_desc;
 bool drm_dp_has_sink_count(struct drm_connector *connector,
 			   const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 			   const struct drm_dp_desc *desc);
+int drm_dp_get_sink_count(struct drm_dp_aux *aux);
 
 void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
 void drm_dp_aux_init(struct drm_dp_aux *aux);
-- 
2.26.2

This is another bit that we never implemented for nouveau: dongle
detection. When a "dongle", e.g. an active display adaptor, is hooked
up
to the system and causes an HPD to be fired, we don't actually know
whether or not there's anything plugged into the dongle without checking
the sink count. As a result, plugging in a dongle without anything
plugged into it currently results in a bogus EDID retrieval error in the kernel
log.

Additionally, most dongles won't send another long HPD signal if the
user suddenly plugs something in, they'll only send a short HPD IRQ with
the expectation that the source will check the sink count and reprobe
the connector if it's changed - something we don't actually do. As a
result, nothing will happen if the user plugs the dongle in before
plugging something into the dongle.

So, let's fix this by checking the sink count in both
nouveau_dp_probe_dpcd() and nouveau_dp_irq(), and reprobing the
connector if things change.

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c      | 54 ++++++++++++++++++++---
 drivers/gpu/drm/nouveau/nouveau_encoder.h |  2 +
 2 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index f6950a62138ca..f41fa513023fd 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -36,12 +36,22 @@ MODULE_PARM_DESC(mst, "Enable DisplayPort multi-stream
(default: enabled)");
 static int nouveau_mst = 1;
 module_param_named(mst, nouveau_mst, int, 0400);
 
+static bool
+nouveau_dp_has_sink_count(struct drm_connector *connector,
+			  struct nouveau_encoder *outp)
+{
+	return drm_dp_has_sink_count(connector, outp->dp.dpcd,
+				     &outp->dp.desc);
+}
+
 static enum drm_connector_status
 nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 		      struct nouveau_encoder *outp)
 {
+	struct drm_connector *connector = &nv_connector->base;
 	struct drm_dp_aux *aux = &nv_connector->aux;
 	struct nv50_mstm *mstm = NULL;
+	enum drm_connector_status status = connector_status_disconnected;
 	int ret;
 	u8 *dpcd = outp->dp.dpcd;
 
@@ -50,9 +60,9 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 		ret = drm_dp_read_desc(aux, &outp->dp.desc,
 				       drm_dp_is_branch(dpcd));
 		if (ret < 0)
-			return connector_status_disconnected;
+			goto out;
 	} else {
-		return connector_status_disconnected;
+		goto out;
 	}
 
 	if (nouveau_mst) {
@@ -61,12 +71,33 @@ nouveau_dp_probe_dpcd(struct nouveau_connector
*nv_connector,
 			mstm->can_mst = drm_dp_has_mst(aux, dpcd);
 	}
 
+	if (nouveau_dp_has_sink_count(connector, outp)) {
+		ret = drm_dp_get_sink_count(aux);
+		if (ret < 0)
+			goto out;
+
+		outp->dp.sink_count = ret;
+
+		/*
+		 * Dongle connected, but no display. Don't bother reading
+		 * downstream port info
+		 */
+		if (!outp->dp.sink_count)
+			return connector_status_disconnected;
+	}
+
 	ret = drm_dp_downstream_read_info(aux, dpcd,
 					  outp->dp.downstream_ports);
 	if (ret < 0)
-		return connector_status_disconnected;
+		goto out;
 
-	return connector_status_connected;
+	status = connector_status_connected;
+out:
+	if (status != connector_status_connected) {
+		/* Clear any cached info */
+		outp->dp.sink_count = 0;
+	}
+	return status;
 }
 
 int
@@ -161,6 +192,8 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 	struct drm_connector *connector = &nv_connector->base;
 	struct nouveau_encoder *outp = find_encoder(connector, DCB_OUTPUT_DP);
 	struct nv50_mstm *mstm;
+	int ret;
+	bool send_hpd = false;
 
 	if (!outp)
 		return;
@@ -172,12 +205,23 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 
 	if (mstm && mstm->is_mst) {
 		if (!nv50_mstm_service(drm, nv_connector, mstm))
-			nouveau_connector_hpd(connector);
+			send_hpd = true;
 	} else {
 		drm_dp_cec_irq(&nv_connector->aux);
+
+		if (nouveau_dp_has_sink_count(connector, outp)) {
+			ret = drm_dp_get_sink_count(&nv_connector->aux);
+			if (ret != outp->dp.sink_count)
+				send_hpd = true;
+			if (ret >= 0)
+				outp->dp.sink_count = ret;
+		}
 	}
 
 	mutex_unlock(&outp->dp.hpd_irq_lock);
+
+	if (send_hpd)
+		nouveau_connector_hpd(connector);
 }
 
 /* TODO:
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h
b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index c1924a4529a7b..21937f1c7dd90 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -74,6 +74,8 @@ struct nouveau_encoder {
 			u8 dpcd[DP_RECEIVER_CAP_SIZE];
 			u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
 			struct drm_dp_desc desc;
+
+			u8 sink_count;
 		} dp;
 	};
 
-- 
2.26.2

Currently in nouveau_connector_ddc_detect() and
nouveau_connector_detect_lvds(), we start the connector probing process
by releasing the previous EDID and informing DRM of the change. However,
since commit 5186421cbfe2 ("drm: Introduce epoch counter to
drm_connector") drm_connector_update_edid_property() actually checks
whether the new EDID we've specified is different from the previous one,
and updates the connector's epoch accordingly if it is. But, because we
always set the EDID to NULL first in nouveau_connector_ddc_detect() and
nouveau_connector_detect_lvds() we end up making DRM think that the EDID
changes every single time we do a connector probe - which isn't needed.

So, let's fix this by not clearing the EDID at the start of the
connector probing process, and instead simply changing or removing it
once near the end of the probing process. This will help prevent us from
sending unneeded hotplug events to userspace when nothing has actually
changed.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 54 ++++++++++-----------
 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 637e91594fbe8..49dd0cbc332ff 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -528,6 +528,17 @@ nouveau_connector_set_encoder(struct drm_connector
*connector,
 	}
 }
 
+static void
+nouveau_connector_set_edid(struct nouveau_connector *nv_connector,
+			   struct edid *edid)
+{
+	struct edid *old_edid = nv_connector->edid;
+
+	drm_connector_update_edid_property(&nv_connector->base, edid);
+	kfree(old_edid);
+	nv_connector->edid = edid;
+}
+
 static enum drm_connector_status
 nouveau_connector_detect(struct drm_connector *connector, bool force)
 {
@@ -541,13 +552,6 @@ nouveau_connector_detect(struct drm_connector *connector,
bool force)
 	int ret;
 	enum drm_connector_status conn_status = connector_status_disconnected;
 
-	/* Cleanup the previous EDID block. */
-	if (nv_connector->edid) {
-		drm_connector_update_edid_property(connector, NULL);
-		kfree(nv_connector->edid);
-		nv_connector->edid = NULL;
-	}
-
 	/* Outputs are only polled while runtime active, so resuming the
 	 * device here is unnecessary (and would deadlock upon runtime suspend
 	 * because it waits for polling to finish). We do however, want to
@@ -560,22 +564,23 @@ nouveau_connector_detect(struct drm_connector *connector,
bool force)
 		ret = pm_runtime_get_sync(dev->dev);
 		if (ret < 0 && ret != -EACCES) {
 			pm_runtime_put_autosuspend(dev->dev);
+			nouveau_connector_set_edid(nv_connector, NULL);
 			return conn_status;
 		}
 	}
 
 	nv_encoder = nouveau_connector_ddc_detect(connector);
 	if (nv_encoder && (i2c = nv_encoder->i2c) != NULL) {
+		struct edid *new_edid;
+
 		if ((vga_switcheroo_handler_flags() &
 		     VGA_SWITCHEROO_CAN_SWITCH_DDC) &&
 		    nv_connector->type == DCB_CONNECTOR_LVDS)
-			nv_connector->edid = drm_get_edid_switcheroo(connector,
-								     i2c);
+			new_edid = drm_get_edid_switcheroo(connector, i2c);
 		else
-			nv_connector->edid = drm_get_edid(connector, i2c);
+			new_edid = drm_get_edid(connector, i2c);
 
-		drm_connector_update_edid_property(connector,
-							nv_connector->edid);
+		nouveau_connector_set_edid(nv_connector, new_edid);
 		if (!nv_connector->edid) {
 			NV_ERROR(drm, "DDC responded, but no EDID for %s\n",
 				 connector->name);
@@ -609,6 +614,8 @@ nouveau_connector_detect(struct drm_connector *connector,
bool force)
 		conn_status = connector_status_connected;
 		drm_dp_cec_set_edid(&nv_connector->aux, nv_connector->edid);
 		goto out;
+	} else {
+		nouveau_connector_set_edid(nv_connector, NULL);
 	}
 
 	nv_encoder = nouveau_connector_of_detect(connector);
@@ -652,18 +659,12 @@ nouveau_connector_detect_lvds(struct drm_connector
*connector, bool force)
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct nouveau_connector *nv_connector = nouveau_connector(connector);
 	struct nouveau_encoder *nv_encoder = NULL;
+	struct edid *edid = NULL;
 	enum drm_connector_status status = connector_status_disconnected;
 
-	/* Cleanup the previous EDID block. */
-	if (nv_connector->edid) {
-		drm_connector_update_edid_property(connector, NULL);
-		kfree(nv_connector->edid);
-		nv_connector->edid = NULL;
-	}
-
 	nv_encoder = find_encoder(connector, DCB_OUTPUT_LVDS);
 	if (!nv_encoder)
-		return connector_status_disconnected;
+		goto out;
 
 	/* Try retrieving EDID via DDC */
 	if (!drm->vbios.fp_no_ddc) {
@@ -682,7 +683,8 @@ nouveau_connector_detect_lvds(struct drm_connector
*connector, bool force)
 	 * valid - it's not (rh#613284)
 	 */
 	if (nv_encoder->dcb->lvdsconf.use_acpi_for_edid) {
-		if ((nv_connector->edid = nouveau_acpi_edid(dev, connector))) {
+		edid = nouveau_acpi_edid(dev, connector);
+		if (edid) {
 			status = connector_status_connected;
 			goto out;
 		}
@@ -702,12 +704,10 @@ nouveau_connector_detect_lvds(struct drm_connector
*connector, bool force)
 	 * stored for the panel stored in them.
 	 */
 	if (!drm->vbios.fp_no_ddc) {
-		struct edid *edid -			(struct edid *)nouveau_bios_embedded_edid(dev);
+		edid = (struct edid *)nouveau_bios_embedded_edid(dev);
 		if (edid) {
-			nv_connector->edid -					kmemdup(edid, EDID_LENGTH, GFP_KERNEL);
-			if (nv_connector->edid)
+			edid = kmemdup(edid, EDID_LENGTH, GFP_KERNEL);
+			if (edid)
 				status = connector_status_connected;
 		}
 	}
@@ -720,7 +720,7 @@ nouveau_connector_detect_lvds(struct drm_connector
*connector, bool force)
 		status = connector_status_unknown;
 #endif
 
-	drm_connector_update_edid_property(connector, nv_connector->edid);
+	nouveau_connector_set_edid(nv_connector, edid);
 	nouveau_connector_set_encoder(connector, nv_encoder);
 	return status;
 }
-- 
2.26.2

Since DP 1.3, it's been possible for DP receivers to specify an
additional set of DPCD capabilities, which can take precedence over the
capabilities reported at DP_DPCD_REV.

Basically any device supporting DP is going to need to read these in an
identical manner, in particular nouveau, so let's go ahead and just move
this code out of i915 into a shared DRM DP helper that we can use in
other drivers.

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/drm_dp_helper.c             | 76 +++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c     | 60 +---------------
 drivers/gpu/drm/i915/display/intel_dp.h     |  1 -
 drivers/gpu/drm/i915/display/intel_lspcon.c |  2 +-
 include/drm/drm_dp_helper.h                 |  3 +
 5 files changed, 82 insertions(+), 60 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 0ff2959c8f8e8..f9445915c6c26 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -423,6 +423,82 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
 }
 EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
 
+static int drm_dp_read_extended_dpcd_caps(struct drm_dp_aux *aux,
+					  u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 dpcd_ext[6];
+	int ret;
+
+	/*
+	 * Prior to DP1.3 the bit represented by
+	 * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved.
+	 * If it is set DP_DPCD_REV at 0000h could be at a value less than
+	 * the true capability of the panel. The only way to check is to
+	 * then compare 0000h and 2200h.
+	 */
+	if (!(dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
+	      DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT))
+		return 0;
+
+	ret = drm_dp_dpcd_read(aux, DP_DP13_DPCD_REV, &dpcd_ext,
+			       sizeof(dpcd_ext));
+	if (ret != sizeof(dpcd_ext))
+		return -EIO;
+
+	if (dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) {
+		DRM_DEBUG_KMS("%s: Extended DPCD rev less than base DPCD rev (%d >
%d)\n",
+			      aux->name, dpcd[DP_DPCD_REV],
+			      dpcd_ext[DP_DPCD_REV]);
+		return 0;
+	}
+
+	if (!memcmp(dpcd, dpcd_ext, sizeof(dpcd_ext)))
+		return 0;
+
+	DRM_DEBUG_KMS("%s: Base DPCD: %*ph\n",
+		      aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
+
+	memcpy(dpcd, dpcd_ext, sizeof(dpcd_ext));
+
+	return 0;
+}
+
+/**
+ * drm_dp_read_dpcd_caps() - read DPCD caps and extended DPCD caps if
+ * available
+ * @aux: DisplayPort AUX channel
+ * @dpcd: Buffer to store the resulting DPCD in
+ *
+ * Attempts to read the base DPCD caps for @aux. Additionally, this function
+ * checks for and reads the extended DPRX caps (%DP_DP13_DPCD_REV) if
+ * present.
+ *
+ * Returns: %0 if the DPCD was read successfully, negative error code
+ * otherwise.
+ */
+int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
+			  u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	int ret;
+
+	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
+	if (ret != DP_RECEIVER_CAP_SIZE || dpcd[DP_DPCD_REV] == 0)
+		return -EIO;
+
+	ret = drm_dp_read_extended_dpcd_caps(aux, dpcd);
+	if (ret < 0)
+		return ret;
+
+	DRM_DEBUG_KMS("%s: DPCD: %*ph\n",
+		      aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
+
+	if (dpcd[DP_DPCD_REV] == 0)
+		ret = -EIO;
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_read_dpcd_caps);
+
 /**
  * drm_dp_downstream_read_info() - read DPCD downstream port info if available
  * @aux: DisplayPort AUX channel
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index e343965a483df..230aa0360dc61 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4449,62 +4449,6 @@ intel_dp_link_down(struct intel_encoder *encoder,
 	}
 }
 
-static void
-intel_dp_extended_receiver_capabilities(struct intel_dp *intel_dp)
-{
-	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
-	u8 dpcd_ext[6];
-
-	/*
-	 * Prior to DP1.3 the bit represented by
-	 * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved.
-	 * if it is set DP_DPCD_REV at 0000h could be at a value less than
-	 * the true capability of the panel. The only way to check is to
-	 * then compare 0000h and 2200h.
-	 */
-	if (!(intel_dp->dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
-	      DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT))
-		return;
-
-	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DP13_DPCD_REV,
-			     &dpcd_ext, sizeof(dpcd_ext)) != sizeof(dpcd_ext)) {
-		drm_err(&i915->drm,
-			"DPCD failed read at extended capabilities\n");
-		return;
-	}
-
-	if (intel_dp->dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) {
-		drm_dbg_kms(&i915->drm,
-			    "DPCD extended DPCD rev less than base DPCD rev\n");
-		return;
-	}
-
-	if (!memcmp(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext)))
-		return;
-
-	drm_dbg_kms(&i915->drm, "Base DPCD: %*ph\n",
-		    (int)sizeof(intel_dp->dpcd), intel_dp->dpcd);
-
-	memcpy(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext));
-}
-
-bool
-intel_dp_read_dpcd(struct intel_dp *intel_dp)
-{
-	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
-
-	if (drm_dp_dpcd_read(&intel_dp->aux, 0x000, intel_dp->dpcd,
-			     sizeof(intel_dp->dpcd)) < 0)
-		return false; /* aux transfer failed */
-
-	intel_dp_extended_receiver_capabilities(intel_dp);
-
-	drm_dbg_kms(&i915->drm, "DPCD: %*ph\n",
(int)sizeof(intel_dp->dpcd),
-		    intel_dp->dpcd);
-
-	return intel_dp->dpcd[DP_DPCD_REV] != 0;
-}
-
 bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
 {
 	u8 dprx = 0;
@@ -4563,7 +4507,7 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
 	/* this function is meant to be called only once */
 	drm_WARN_ON(&dev_priv->drm, intel_dp->dpcd[DP_DPCD_REV] != 0);
 
-	if (!intel_dp_read_dpcd(intel_dp))
+	if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd) != 0)
 		return false;
 
 	drm_dp_read_desc(&intel_dp->aux, &intel_dp->desc,
@@ -4650,7 +4594,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 {
 	int ret;
 
-	if (!intel_dp_read_dpcd(intel_dp))
+	if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd))
 		return false;
 
 	/*
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h
b/drivers/gpu/drm/i915/display/intel_dp.h
index b901ab850cbd9..0a3af3410d52e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -99,7 +99,6 @@ bool intel_dp_source_supports_hbr3(struct intel_dp *intel_dp);
 bool
 intel_dp_get_link_status(struct intel_dp *intel_dp, u8 *link_status);
 
-bool intel_dp_read_dpcd(struct intel_dp *intel_dp);
 bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp);
 int intel_dp_link_required(int pixel_clock, int bpp);
 int intel_dp_max_data_rate(int max_link_clock, int max_lanes);
diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c
b/drivers/gpu/drm/i915/display/intel_lspcon.c
index b781bf4696443..dc1b35559afdf 100644
--- a/drivers/gpu/drm/i915/display/intel_lspcon.c
+++ b/drivers/gpu/drm/i915/display/intel_lspcon.c
@@ -571,7 +571,7 @@ bool lspcon_init(struct intel_digital_port *dig_port)
 		return false;
 	}
 
-	if (!intel_dp_read_dpcd(dp)) {
+	if (drm_dp_read_dpcd_caps(&dp->aux, dp->dpcd) != 0) {
 		DRM_ERROR("LSPCON DPCD read failed\n");
 		return false;
 	}
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 0c141fc81aaa8..11649e93e5bb6 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1607,6 +1607,9 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux
*aux,
 	return drm_dp_dpcd_write(aux, offset, &value, 1);
 }
 
+int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
+			  u8 dpcd[DP_RECEIVER_CAP_SIZE]);
+
 int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 				 u8 status[DP_LINK_STATUS_SIZE]);
 
-- 
2.26.2

Now that we've extracted i915's code for reading both the normal DPCD
caps and extended DPCD caps into a shared helper, let's start using this
in nouveau to enable us to start checking extended DPCD caps for free.

Signed-off-by: Lyude Paul <lyude at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
index f41fa513023fd..a4e07d116972f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -55,15 +55,13 @@ nouveau_dp_probe_dpcd(struct nouveau_connector
*nv_connector,
 	int ret;
 	u8 *dpcd = outp->dp.dpcd;
 
-	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
-	if (ret == DP_RECEIVER_CAP_SIZE && dpcd[DP_DPCD_REV]) {
-		ret = drm_dp_read_desc(aux, &outp->dp.desc,
-				       drm_dp_is_branch(dpcd));
-		if (ret < 0)
-			goto out;
-	} else {
+	ret = drm_dp_read_dpcd_caps(aux, dpcd);
+	if (ret < 0)
+		goto out;
+
+	ret = drm_dp_read_desc(aux, &outp->dp.desc, drm_dp_is_branch(dpcd));
+	if (ret < 0)
 		goto out;
-	}
 
 	if (nouveau_mst) {
 		mstm = outp->dp.mstm;
-- 
2.26.2

On Wed, 12 Aug 2020 at 06:05, Lyude Paul <lyude at redhat.com>
wrote:
>
> Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_dp.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
> index 8a0f7994e1aeb..ee778ddc95fae 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dp.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
> @@ -76,10 +76,10 @@ nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
>         nv_encoder->dp.link_nr = dpcd[2] & DP_MAX_LANE_COUNT_MASK;
>
>         NV_DEBUG(drm, "display: %dx%d dpcd 0x%02x\n",
> -                    nv_encoder->dp.link_nr, nv_encoder->dp.link_bw,
dpcd[0]);
> +                nv_encoder->dp.link_nr, nv_encoder->dp.link_bw,
dpcd[0]);
>         NV_DEBUG(drm, "encoder: %dx%d\n",
> -                    nv_encoder->dcb->dpconf.link_nr,
> -                    nv_encoder->dcb->dpconf.link_bw);
> +                nv_encoder->dcb->dpconf.link_nr,
> +                nv_encoder->dcb->dpconf.link_bw);
>
>         if (nv_encoder->dcb->dpconf.link_nr <
nv_encoder->dp.link_nr)
>                 nv_encoder->dp.link_nr =
nv_encoder->dcb->dpconf.link_nr;
> @@ -87,7 +87,7 @@ nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
>                 nv_encoder->dp.link_bw =
nv_encoder->dcb->dpconf.link_bw;
>
>         NV_DEBUG(drm, "maximum: %dx%d\n",
> -                    nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
> +                nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
>
>         nouveau_dp_probe_oui(dev, aux, dpcd);
>
> --
> 2.26.2
>
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

On Wed, 12 Aug 2020 at 06:06, Lyude Paul <lyude at redhat.com>
wrote:
>
> Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_dp.c | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
> index d701f09aea645..bb85d81c25244 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dp.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
> @@ -44,7 +44,6 @@ nouveau_dp_probe_dpcd(struct nouveau_connector
*nv_connector,
>         struct nv50_mstm *mstm = NULL;
>         int ret;
>         u8 *dpcd = outp->dp.dpcd;
> -       u8 tmp;
>
>         ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd,
DP_RECEIVER_CAP_SIZE);
>         if (ret == DP_RECEIVER_CAP_SIZE && dpcd[DP_DPCD_REV]) {
> @@ -56,19 +55,10 @@ nouveau_dp_probe_dpcd(struct nouveau_connector
*nv_connector,
>                 return connector_status_disconnected;
>         }
>
> -       if (nouveau_mst)
> +       if (nouveau_mst) {
>                 mstm = outp->dp.mstm;
> -
> -       if (mstm) {
> -               if (dpcd[DP_DPCD_REV] >= DP_DPCD_REV_12) {
> -                       ret = drm_dp_dpcd_readb(aux, DP_MSTM_CAP,
&tmp);
> -                       if (ret < 0)
> -                               return connector_status_disconnected;
> -
> -                       mstm->can_mst = !!(tmp & DP_MST_CAP);
> -               } else {
> -                       mstm->can_mst = false;
> -               }
> +               if (mstm)
> +                       mstm->can_mst = drm_dp_has_mst(aux, dpcd);
>         }
>
>         return connector_status_connected;
> --
> 2.26.2
>
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

On Wed, 12 Aug 2020 at 06:06, Lyude Paul <lyude at redhat.com>
wrote:
>
> This is another bit that we never implemented for nouveau: dongle
> detection. When a "dongle", e.g. an active display adaptor, is
hooked up
> to the system and causes an HPD to be fired, we don't actually know
> whether or not there's anything plugged into the dongle without
checking
> the sink count. As a result, plugging in a dongle without anything
> plugged into it currently results in a bogus EDID retrieval error in the
kernel log.
>
> Additionally, most dongles won't send another long HPD signal if the
> user suddenly plugs something in, they'll only send a short HPD IRQ
with
> the expectation that the source will check the sink count and reprobe
> the connector if it's changed - something we don't actually do. As
a
> result, nothing will happen if the user plugs the dongle in before
> plugging something into the dongle.
>
> So, let's fix this by checking the sink count in both
> nouveau_dp_probe_dpcd() and nouveau_dp_irq(), and reprobing the
> connector if things change.
>
> Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_dp.c      | 54 ++++++++++++++++++++---
>  drivers/gpu/drm/nouveau/nouveau_encoder.h |  2 +
>  2 files changed, 51 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
> index f6950a62138ca..f41fa513023fd 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dp.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
> @@ -36,12 +36,22 @@ MODULE_PARM_DESC(mst, "Enable DisplayPort
multi-stream (default: enabled)");
>  static int nouveau_mst = 1;
>  module_param_named(mst, nouveau_mst, int, 0400);
>
> +static bool
> +nouveau_dp_has_sink_count(struct drm_connector *connector,
> +                         struct nouveau_encoder *outp)
> +{
> +       return drm_dp_has_sink_count(connector, outp->dp.dpcd,
> +                                    &outp->dp.desc);
> +}
> +
>  static enum drm_connector_status
>  nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
>                       struct nouveau_encoder *outp)
>  {
> +       struct drm_connector *connector = &nv_connector->base;
>         struct drm_dp_aux *aux = &nv_connector->aux;
>         struct nv50_mstm *mstm = NULL;
> +       enum drm_connector_status status = connector_status_disconnected;
>         int ret;
>         u8 *dpcd = outp->dp.dpcd;
>
> @@ -50,9 +60,9 @@ nouveau_dp_probe_dpcd(struct nouveau_connector
*nv_connector,
>                 ret = drm_dp_read_desc(aux, &outp->dp.desc,
>                                        drm_dp_is_branch(dpcd));
>                 if (ret < 0)
> -                       return connector_status_disconnected;
> +                       goto out;
>         } else {
> -               return connector_status_disconnected;
> +               goto out;
>         }
>
>         if (nouveau_mst) {
> @@ -61,12 +71,33 @@ nouveau_dp_probe_dpcd(struct nouveau_connector
*nv_connector,
>                         mstm->can_mst = drm_dp_has_mst(aux, dpcd);
>         }
>
> +       if (nouveau_dp_has_sink_count(connector, outp)) {
> +               ret = drm_dp_get_sink_count(aux);
> +               if (ret < 0)
> +                       goto out;
> +
> +               outp->dp.sink_count = ret;
> +
> +               /*
> +                * Dongle connected, but no display. Don't bother
reading
> +                * downstream port info
> +                */
> +               if (!outp->dp.sink_count)
> +                       return connector_status_disconnected;
> +       }
> +
>         ret = drm_dp_downstream_read_info(aux, dpcd,
>                                           outp->dp.downstream_ports);
>         if (ret < 0)
> -               return connector_status_disconnected;
> +               goto out;
>
> -       return connector_status_connected;
> +       status = connector_status_connected;
> +out:
> +       if (status != connector_status_connected) {
> +               /* Clear any cached info */
> +               outp->dp.sink_count = 0;
> +       }
> +       return status;
>  }
>
>  int
> @@ -161,6 +192,8 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
>         struct drm_connector *connector = &nv_connector->base;
>         struct nouveau_encoder *outp = find_encoder(connector,
DCB_OUTPUT_DP);
>         struct nv50_mstm *mstm;
> +       int ret;
> +       bool send_hpd = false;
>
>         if (!outp)
>                 return;
> @@ -172,12 +205,23 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
>
>         if (mstm && mstm->is_mst) {
>                 if (!nv50_mstm_service(drm, nv_connector, mstm))
> -                       nouveau_connector_hpd(connector);
> +                       send_hpd = true;
>         } else {
>                 drm_dp_cec_irq(&nv_connector->aux);
> +
> +               if (nouveau_dp_has_sink_count(connector, outp)) {
> +                       ret =
drm_dp_get_sink_count(&nv_connector->aux);
> +                       if (ret != outp->dp.sink_count)
> +                               send_hpd = true;
> +                       if (ret >= 0)
> +                               outp->dp.sink_count = ret;
> +               }
>         }
>
>         mutex_unlock(&outp->dp.hpd_irq_lock);
> +
> +       if (send_hpd)
> +               nouveau_connector_hpd(connector);
>  }
>
>  /* TODO:
> diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h
b/drivers/gpu/drm/nouveau/nouveau_encoder.h
> index c1924a4529a7b..21937f1c7dd90 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
> @@ -74,6 +74,8 @@ struct nouveau_encoder {
>                         u8 dpcd[DP_RECEIVER_CAP_SIZE];
>                         u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
>                         struct drm_dp_desc desc;
> +
> +                       u8 sink_count;
>                 } dp;
>         };
>
> --
> 2.26.2
>
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

On Wed, 12 Aug 2020 at 06:07, Lyude Paul <lyude at redhat.com>
wrote:
>
> Now that we've extracted i915's code for reading both the normal
DPCD
> caps and extended DPCD caps into a shared helper, let's start using
this
> in nouveau to enable us to start checking extended DPCD caps for free.
>
> Signed-off-by: Lyude Paul <lyude at redhat.com>
Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_dp.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
> index f41fa513023fd..a4e07d116972f 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dp.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
> @@ -55,15 +55,13 @@ nouveau_dp_probe_dpcd(struct nouveau_connector
*nv_connector,
>         int ret;
>         u8 *dpcd = outp->dp.dpcd;
>
> -       ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd,
DP_RECEIVER_CAP_SIZE);
> -       if (ret == DP_RECEIVER_CAP_SIZE && dpcd[DP_DPCD_REV]) {
> -               ret = drm_dp_read_desc(aux, &outp->dp.desc,
> -                                      drm_dp_is_branch(dpcd));
> -               if (ret < 0)
> -                       goto out;
> -       } else {
> +       ret = drm_dp_read_dpcd_caps(aux, dpcd);
> +       if (ret < 0)
> +               goto out;
> +
> +       ret = drm_dp_read_desc(aux, &outp->dp.desc,
drm_dp_is_branch(dpcd));
> +       if (ret < 0)
>                 goto out;
> -       }
>
>         if (nouveau_mst) {
>                 mstm = outp->dp.mstm;
> --
> 2.26.2
>
> _______________________________________________
> Nouveau mailing list
> Nouveau at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/nouveau

On Tue, Aug 11, 2020 at 04:04:46PM -0400, Lyude Paul
wrote:
> Just a tiny drive-by cleanup, we can consolidate i915's code for
> checking for MST support into a helper to be shared across drivers.
> 
Reviewed-by: Sean Paul <sean at poorly.run>
> Signed-off-by: Lyude Paul <lyude at redhat.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 18 ++----------------
>  include/drm/drm_dp_mst_helper.h         | 22 ++++++++++++++++++++++
>  2 files changed, 24 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
> index 79c27f91f42c0..1e29d3a012856 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4699,20 +4699,6 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  	return true;
>  }
>  
> -static bool
> -intel_dp_sink_can_mst(struct intel_dp *intel_dp)
> -{
> -	u8 mstm_cap;
> -
> -	if (intel_dp->dpcd[DP_DPCD_REV] < 0x12)
> -		return false;
> -
> -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_MSTM_CAP, &mstm_cap)
!= 1)
> -		return false;
> -
> -	return mstm_cap & DP_MST_CAP;
> -}
> -
>  static bool
>  intel_dp_can_mst(struct intel_dp *intel_dp)
>  {
> @@ -4720,7 +4706,7 @@ intel_dp_can_mst(struct intel_dp *intel_dp)
>  
>  	return i915->params.enable_dp_mst &&
>  		intel_dp->can_mst &&
> -		intel_dp_sink_can_mst(intel_dp);
> +		drm_dp_has_mst(&intel_dp->aux, intel_dp->dpcd);
>  }
>  
>  static void
> @@ -4729,7 +4715,7 @@ intel_dp_configure_mst(struct intel_dp *intel_dp)
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  	struct intel_encoder *encoder >  	
&dp_to_dig_port(intel_dp)->base;
> -	bool sink_can_mst = intel_dp_sink_can_mst(intel_dp);
> +	bool sink_can_mst = drm_dp_has_mst(&intel_dp->aux,
intel_dp->dpcd);
>  
>  	drm_dbg_kms(&i915->drm,
>  		    "[ENCODER:%d:%s] MST support: port: %s, sink: %s, modparam:
%s\n",
> diff --git a/include/drm/drm_dp_mst_helper.h
b/include/drm/drm_dp_mst_helper.h
> index 8b9eb4db3381c..2d8983a713e8c 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -911,4 +911,26 @@ __drm_dp_mst_state_iter_get(struct drm_atomic_state
*state,
>  	for ((__i) = 0; (__i) < (__state)->num_private_objs; (__i)++) \
>  		for_each_if(__drm_dp_mst_state_iter_get((__state), &(mgr), NULL,
&(new_state), (__i)))
>  
> +/**
> + * drm_dp_has_mst() - check whether or not a sink supports MST
> + * @aux: The DP AUX channel to use
> + * @dpcd: A cached copy of the DPCD capabilities for this sink
> + *
> + * Returns: %True if the sink supports MST, %false otherwise
> + */
> +static inline bool
> +drm_dp_has_mst(struct drm_dp_aux *aux,
> +	       const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> +{
> +	u8 mstm_cap;
> +
> +	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
> +		return false;
> +
> +	if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
> +		return false;
> +
> +	return !!(mstm_cap & DP_MST_CAP);
> +}
> +
>  #endif
> -- 
> 2.26.2
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 
Sean Paul, Software Engineer, Google / Chromium OS

On Tue, Aug 11, 2020 at 04:04:50PM -0400, Lyude Paul
wrote:
> We're going to be doing the same probing process in nouveau for
> determining downstream DP port capabilities, so let's deduplicate the
> work by moving i915's code for handling this into a shared helper:
> drm_dp_downstream_read_info().
> 
> Note that when we do this, we also do make some functional changes while
> we're at it:
> * We always clear the downstream port info before trying to read it,
>   just to make things easier for the caller
> * We skip reading downstream port info if the DPCD indicates that we
>   don't support downstream port info
> * We only read as many bytes as needed for the reported number of
>   downstream ports, no sense in reading the whole thing every time
> 
> Signed-off-by: Lyude Paul <lyude at redhat.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c         | 32 +++++++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp.c | 14 ++---------
>  include/drm/drm_dp_helper.h             |  3 +++
>  3 files changed, 37 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c
b/drivers/gpu/drm/drm_dp_helper.c
> index 4c21cf69dad5a..9703b33599c3b 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -423,6 +423,38 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux
*aux,
>  }
>  EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
>  
> +/**
> + * drm_dp_downstream_read_info() - read DPCD downstream port info if
available
> + * @aux: DisplayPort AUX channel
> + * @dpcd: A cached copy of the port's DPCD
> + * @downstream_ports: buffer to store the downstream port info in
> + *
> + * Returns: 0 if either the downstream port info was read successfully or
> + * there was no downstream info to read, or a negative error code
otherwise.
> + */
> +int drm_dp_downstream_read_info(struct drm_dp_aux *aux,
> +				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> +				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS])
> +{
> +	int ret;
> +	u8 len;
> +
> +	memset(downstream_ports, 0, DP_MAX_DOWNSTREAM_PORTS);
> +
> +	/* No downstream info to read */
> +	if (!drm_dp_is_branch(dpcd) ||
> +	    dpcd[DP_DPCD_REV] < DP_DPCD_REV_10 ||
> +	    !(dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT))
> +		return 0;
> +
> +	len = (dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_PORT_COUNT_MASK) * 4;
I'm having a hard time rationalizing DP_MAX_DOWNSTREAM_PORTS being 16, but
only
having 4 ports worth of data in the DP_DOWNSTREAM_PORT_* registers. Do you know
what's supposed to happen if dpcd[DP_DOWN_STREAM_PORT_COUNT] is > 4?

Sean
> +	ret = drm_dp_dpcd_read(aux, DP_DOWNSTREAM_PORT_0, downstream_ports,
> +			       len);
> +
> +	return ret == len ? 0 : -EIO;
> +}
> +EXPORT_SYMBOL(drm_dp_downstream_read_info);
> +
>  /**
>   * drm_dp_downstream_max_clock() - extract branch device max
>   *                                 pixel rate for legacy VGA
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
> index 1e29d3a012856..984e49194ca31 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4685,18 +4685,8 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  			return false;
>  	}
>  
> -	if (!drm_dp_is_branch(intel_dp->dpcd))
> -		return true; /* native DP sink */
> -
> -	if (intel_dp->dpcd[DP_DPCD_REV] == 0x10)
> -		return true; /* no per-port downstream info */
> -
> -	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DOWNSTREAM_PORT_0,
> -			     intel_dp->downstream_ports,
> -			     DP_MAX_DOWNSTREAM_PORTS) < 0)
> -		return false; /* downstream port status fetch failed */
> -
> -	return true;
> +	return drm_dp_downstream_read_info(&intel_dp->aux,
intel_dp->dpcd,
> +					   intel_dp->downstream_ports) == 0;
>  }
>  
>  static bool
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 5c28199248626..1349f16564ace 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1613,6 +1613,9 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux
*aux,
>  bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
>  				    u8 real_edid_checksum);
>  
> +int drm_dp_downstream_read_info(struct drm_dp_aux *aux,
> +				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> +				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS]);
>  int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
>  				const u8 port_cap[4]);
>  int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> -- 
> 2.26.2
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 
Sean Paul, Software Engineer, Google / Chromium OS

On Tue, Aug 11, 2020 at 04:04:52PM -0400, Lyude Paul
wrote:
> Since other drivers are also going to need to be aware of the sink count
> in order to do proper dongle detection, we might as well steal i915's
> DP_SINK_COUNT helpers and move them into DRM helpers so that other
> dirvers can use them as well.
> 
> Note that this also starts using intel_dp_has_sink_count() in
> intel_dp_detect_dpcd(), which is a functional change.
> 
Reviewed-by: Sean Paul <sean at poorly.run>
> Signed-off-by: Lyude Paul <lyude at redhat.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c         | 22 ++++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp.c | 21 ++++++++++++---------
>  include/drm/drm_dp_helper.h             |  8 +++++++-
>  3 files changed, 41 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c
b/drivers/gpu/drm/drm_dp_helper.c
> index 9703b33599c3b..05bb47e589731 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -700,6 +700,28 @@ void drm_dp_set_subconnector_property(struct
drm_connector *connector,
>  }
>  EXPORT_SYMBOL(drm_dp_set_subconnector_property);
>  
> +/**
> + * drm_dp_has_sink_count() - Check whether a given connector has a valid
sink
> + * count
> + * @connector: The DRM connector to check
> + * @dpcd: A cached copy of the connector's DPCD RX capabilities
> + * @desc: A cached copy of the connector's DP descriptor
> + *
> + * Returns: %True if the (e)DP connector has a valid sink count that
should
> + * be probed, %false otherwise.
> + */
> +bool drm_dp_has_sink_count(struct drm_connector *connector,
> +			   const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> +			   const struct drm_dp_desc *desc)
> +{
> +	/* Some eDP panels don't set a valid value for the sink count */
> +	return connector->connector_type != DRM_MODE_CONNECTOR_eDP &&
> +		dpcd[DP_DPCD_REV] >= DP_DPCD_REV_11 &&
> +		dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT
&&
> +		!drm_dp_has_quirk(desc, 0, DP_DPCD_QUIRK_NO_SINK_COUNT);
> +}
> +EXPORT_SYMBOL(drm_dp_has_sink_count);
> +
>  /*
>   * I2C-over-AUX implementation
>   */
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
> index 984e49194ca31..35a4779a442e2 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4634,6 +4634,16 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
>  	return true;
>  }
>  
> +static bool
> +intel_dp_has_sink_count(struct intel_dp *intel_dp)
> +{
> +	if (!intel_dp->attached_connector)
> +		return false;
> +
> +	return
drm_dp_has_sink_count(&intel_dp->attached_connector->base,
> +				     intel_dp->dpcd,
> +				     &intel_dp->desc);
> +}
>  
>  static bool
>  intel_dp_get_dpcd(struct intel_dp *intel_dp)
> @@ -4653,13 +4663,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  		intel_dp_set_common_rates(intel_dp);
>  	}
>  
> -	/*
> -	 * Some eDP panels do not set a valid value for sink count, that is why
> -	 * it don't care about read it here and in intel_edp_init_dpcd().
> -	 */
> -	if (!intel_dp_is_edp(intel_dp) &&
> -	    !drm_dp_has_quirk(&intel_dp->desc, 0,
> -			      DP_DPCD_QUIRK_NO_SINK_COUNT)) {
> +	if (intel_dp_has_sink_count(intel_dp)) {
>  		u8 count;
>  		ssize_t r;
>  
> @@ -5939,9 +5943,8 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
>  		return connector_status_connected;
>  
>  	/* If we're HPD-aware, SINK_COUNT changes dynamically */
> -	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
> +	if (intel_dp_has_sink_count(intel_dp) &&
>  	    intel_dp->downstream_ports[0] & DP_DS_PORT_HPD) {
> -
>  		return intel_dp->sink_count ?
>  		connector_status_connected : connector_status_disconnected;
>  	}
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 1349f16564ace..a1413a531eaf4 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1631,6 +1631,11 @@ void drm_dp_set_subconnector_property(struct
drm_connector *connector,
>  				      const u8 *dpcd,
>  				      const u8 port_cap[4]);
>  
> +struct drm_dp_desc;
> +bool drm_dp_has_sink_count(struct drm_connector *connector,
> +			   const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> +			   const struct drm_dp_desc *desc);
> +
>  void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
>  void drm_dp_aux_init(struct drm_dp_aux *aux);
>  int drm_dp_aux_register(struct drm_dp_aux *aux);
> @@ -1689,7 +1694,8 @@ enum drm_dp_quirk {
>  	 * @DP_DPCD_QUIRK_NO_SINK_COUNT:
>  	 *
>  	 * The device does not set SINK_COUNT to a non-zero value.
> -	 * The driver should ignore SINK_COUNT during detection.
> +	 * The driver should ignore SINK_COUNT during detection. Note that
> +	 * drm_dp_has_sink_count() automatically checks for this quirk.
>  	 */
>  	DP_DPCD_QUIRK_NO_SINK_COUNT,
>  	/**
> -- 
> 2.26.2
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 
Sean Paul, Software Engineer, Google / Chromium OS

On Tue, Aug 11, 2020 at 04:04:53PM -0400, Lyude Paul
wrote:
> And of course, we'll also need to read the sink count from other
drivers
> as well if we're checking whether or not it's supported. So,
let's
> extract the code for this into another helper.
> 
> Signed-off-by: Lyude Paul <lyude at redhat.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c         | 20 ++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp.c | 17 +++++------------
>  include/drm/drm_dp_helper.h             |  1 +
>  3 files changed, 26 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c
b/drivers/gpu/drm/drm_dp_helper.c
> index 05bb47e589731..0ff2959c8f8e8 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -722,6 +722,26 @@ bool drm_dp_has_sink_count(struct drm_connector
*connector,
>  }
>  EXPORT_SYMBOL(drm_dp_has_sink_count);
>  
> +/**
> + * drm_dp_get_sink_count() - Retrieve the sink count for a given sink
> + * @aux: The DP AUX channel to use
> + *
> + * Returns: The current sink count reported by @aux, or a negative error
code
> + * otherwise.
> + */
> +int drm_dp_get_sink_count(struct drm_dp_aux *aux)
> +{
> +	u8 count;
> +	int ret;
> +
> +	ret = drm_dp_dpcd_readb(aux, DP_SINK_COUNT, &count);
> +	if (ret < 1)
> +		return -EIO;
This should probably be:
        if (ret < 0)
                return ret;
        else if (ret != 1)
                return -EIO;

> +
> +	return DP_GET_SINK_COUNT(count);
> +}
> +EXPORT_SYMBOL(drm_dp_get_sink_count);
> +
>  /*
>   * I2C-over-AUX implementation
>   */
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
> index 35a4779a442e2..e343965a483df 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4648,6 +4648,8 @@ intel_dp_has_sink_count(struct intel_dp *intel_dp)
>  static bool
>  intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  {
> +	int ret;
> +
>  	if (!intel_dp_read_dpcd(intel_dp))
>  		return false;
>  
> @@ -4664,20 +4666,10 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  	}
>  
>  	if (intel_dp_has_sink_count(intel_dp)) {
> -		u8 count;
> -		ssize_t r;
> -
> -		r = drm_dp_dpcd_readb(&intel_dp->aux, DP_SINK_COUNT, &count);
> -		if (r < 1)
> +		ret = drm_dp_get_sink_count(&intel_dp->aux);
> +		if (ret < 0)
>  			return false;
>  
> -		/*
> -		 * Sink count can change between short pulse hpd hence
> -		 * a member variable in intel_dp will track any changes
> -		 * between short pulse interrupts.
> -		 */
I think you could probably keep this comment and relocate the
intel_dp->sink_count
assignment back.

With these nits (or something like them),

Reviewed-by: Sean Paul <sean at poorly.run>
> -		intel_dp->sink_count = DP_GET_SINK_COUNT(count);
> -
>  		/*
>  		 * SINK_COUNT == 0 and DOWNSTREAM_PORT_PRESENT == 1 implies that
>  		 * a dongle is present but no display. Unless we require to know
> @@ -4685,6 +4677,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  		 * downstream port information. So, an early return here saves
>  		 * time from performing other operations which are not required.
>  		 */
> +		intel_dp->sink_count = ret;
>  		if (!intel_dp->sink_count)
>  			return false;
>  	}
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index a1413a531eaf4..0c141fc81aaa8 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1635,6 +1635,7 @@ struct drm_dp_desc;
>  bool drm_dp_has_sink_count(struct drm_connector *connector,
>  			   const u8 dpcd[DP_RECEIVER_CAP_SIZE],
>  			   const struct drm_dp_desc *desc);
> +int drm_dp_get_sink_count(struct drm_dp_aux *aux);
>  
>  void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
>  void drm_dp_aux_init(struct drm_dp_aux *aux);
> -- 
> 2.26.2
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 
Sean Paul, Software Engineer, Google / Chromium OS

On Tue, Aug 11, 2020 at 04:04:56PM -0400, Lyude Paul
wrote:
> Since DP 1.3, it's been possible for DP receivers to specify an
> additional set of DPCD capabilities, which can take precedence over the
> capabilities reported at DP_DPCD_REV.
> 
> Basically any device supporting DP is going to need to read these in an
> identical manner, in particular nouveau, so let's go ahead and just
move
> this code out of i915 into a shared DRM DP helper that we can use in
> other drivers.
> 
> Signed-off-by: Lyude Paul <lyude at redhat.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c             | 76 +++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp.c     | 60 +---------------
>  drivers/gpu/drm/i915/display/intel_dp.h     |  1 -
>  drivers/gpu/drm/i915/display/intel_lspcon.c |  2 +-
>  include/drm/drm_dp_helper.h                 |  3 +
>  5 files changed, 82 insertions(+), 60 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c
b/drivers/gpu/drm/drm_dp_helper.c
> index 0ff2959c8f8e8..f9445915c6c26 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -423,6 +423,82 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux
*aux,
>  }
>  EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
>  
> +static int drm_dp_read_extended_dpcd_caps(struct drm_dp_aux *aux,
> +					  u8 dpcd[DP_RECEIVER_CAP_SIZE])
> +{
> +	u8 dpcd_ext[6];
> +	int ret;
> +
> +	/*
> +	 * Prior to DP1.3 the bit represented by
> +	 * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved.
> +	 * If it is set DP_DPCD_REV at 0000h could be at a value less than
> +	 * the true capability of the panel. The only way to check is to
> +	 * then compare 0000h and 2200h.
> +	 */
> +	if (!(dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
> +	      DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT))
> +		return 0;
> +
> +	ret = drm_dp_dpcd_read(aux, DP_DP13_DPCD_REV, &dpcd_ext,
> +			       sizeof(dpcd_ext));
> +	if (ret != sizeof(dpcd_ext))
> +		return -EIO;
> +
> +	if (dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) {
> +		DRM_DEBUG_KMS("%s: Extended DPCD rev less than base DPCD rev (%d
> %d)\n",
> +			      aux->name, dpcd[DP_DPCD_REV],
> +			      dpcd_ext[DP_DPCD_REV]);
Might be a good opportunity to convert all of these to drm_dbg_dp()?
> +		return 0;
> +	}
> +
> +	if (!memcmp(dpcd, dpcd_ext, sizeof(dpcd_ext)))
> +		return 0;
> +
> +	DRM_DEBUG_KMS("%s: Base DPCD: %*ph\n",
> +		      aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
> +
> +	memcpy(dpcd, dpcd_ext, sizeof(dpcd_ext));
> +
> +	return 0;
> +}
> +
> +/**
> + * drm_dp_read_dpcd_caps() - read DPCD caps and extended DPCD caps if
> + * available
> + * @aux: DisplayPort AUX channel
> + * @dpcd: Buffer to store the resulting DPCD in
> + *
> + * Attempts to read the base DPCD caps for @aux. Additionally, this
function
> + * checks for and reads the extended DPRX caps (%DP_DP13_DPCD_REV) if
> + * present.
> + *
> + * Returns: %0 if the DPCD was read successfully, negative error code
> + * otherwise.
> + */
> +int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
> +			  u8 dpcd[DP_RECEIVER_CAP_SIZE])
> +{
> +	int ret;
> +
> +	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
> +	if (ret != DP_RECEIVER_CAP_SIZE || dpcd[DP_DPCD_REV] == 0)
> +		return -EIO;
> +
> +	ret = drm_dp_read_extended_dpcd_caps(aux, dpcd);
> +	if (ret < 0)
> +		return ret;
I wonder if we should just go with the "regular" dpcd caps we just
read in this
case?

Regardless of my nits,

Reviewed-by: Sean Paul <sean at poorly.run>
> +
> +	DRM_DEBUG_KMS("%s: DPCD: %*ph\n",
> +		      aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
> +
> +	if (dpcd[DP_DPCD_REV] == 0)
> +		ret = -EIO;
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(drm_dp_read_dpcd_caps);
> +
>  /**
>   * drm_dp_downstream_read_info() - read DPCD downstream port info if
available
>   * @aux: DisplayPort AUX channel
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
> index e343965a483df..230aa0360dc61 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4449,62 +4449,6 @@ intel_dp_link_down(struct intel_encoder *encoder,
>  	}
>  }
>  
> -static void
> -intel_dp_extended_receiver_capabilities(struct intel_dp *intel_dp)
> -{
> -	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> -	u8 dpcd_ext[6];
> -
> -	/*
> -	 * Prior to DP1.3 the bit represented by
> -	 * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved.
> -	 * if it is set DP_DPCD_REV at 0000h could be at a value less than
> -	 * the true capability of the panel. The only way to check is to
> -	 * then compare 0000h and 2200h.
> -	 */
> -	if (!(intel_dp->dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
> -	      DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT))
> -		return;
> -
> -	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DP13_DPCD_REV,
> -			     &dpcd_ext, sizeof(dpcd_ext)) != sizeof(dpcd_ext)) {
> -		drm_err(&i915->drm,
> -			"DPCD failed read at extended capabilities\n");
> -		return;
> -	}
> -
> -	if (intel_dp->dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) {
> -		drm_dbg_kms(&i915->drm,
> -			    "DPCD extended DPCD rev less than base DPCD rev\n");
> -		return;
> -	}
> -
> -	if (!memcmp(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext)))
> -		return;
> -
> -	drm_dbg_kms(&i915->drm, "Base DPCD: %*ph\n",
> -		    (int)sizeof(intel_dp->dpcd), intel_dp->dpcd);
> -
> -	memcpy(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext));
> -}
> -
> -bool
> -intel_dp_read_dpcd(struct intel_dp *intel_dp)
> -{
> -	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> -
> -	if (drm_dp_dpcd_read(&intel_dp->aux, 0x000, intel_dp->dpcd,
> -			     sizeof(intel_dp->dpcd)) < 0)
> -		return false; /* aux transfer failed */
> -
> -	intel_dp_extended_receiver_capabilities(intel_dp);
> -
> -	drm_dbg_kms(&i915->drm, "DPCD: %*ph\n",
(int)sizeof(intel_dp->dpcd),
> -		    intel_dp->dpcd);
> -
> -	return intel_dp->dpcd[DP_DPCD_REV] != 0;
> -}
> -
>  bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
>  {
>  	u8 dprx = 0;
> @@ -4563,7 +4507,7 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
>  	/* this function is meant to be called only once */
>  	drm_WARN_ON(&dev_priv->drm, intel_dp->dpcd[DP_DPCD_REV] != 0);
>  
> -	if (!intel_dp_read_dpcd(intel_dp))
> +	if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd) != 0)
>  		return false;
>  
>  	drm_dp_read_desc(&intel_dp->aux, &intel_dp->desc,
> @@ -4650,7 +4594,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  {
>  	int ret;
>  
> -	if (!intel_dp_read_dpcd(intel_dp))
> +	if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd))
>  		return false;
>  
>  	/*
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.h
b/drivers/gpu/drm/i915/display/intel_dp.h
> index b901ab850cbd9..0a3af3410d52e 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp.h
> @@ -99,7 +99,6 @@ bool intel_dp_source_supports_hbr3(struct intel_dp
*intel_dp);
>  bool
>  intel_dp_get_link_status(struct intel_dp *intel_dp, u8 *link_status);
>  
> -bool intel_dp_read_dpcd(struct intel_dp *intel_dp);
>  bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp);
>  int intel_dp_link_required(int pixel_clock, int bpp);
>  int intel_dp_max_data_rate(int max_link_clock, int max_lanes);
> diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c
b/drivers/gpu/drm/i915/display/intel_lspcon.c
> index b781bf4696443..dc1b35559afdf 100644
> --- a/drivers/gpu/drm/i915/display/intel_lspcon.c
> +++ b/drivers/gpu/drm/i915/display/intel_lspcon.c
> @@ -571,7 +571,7 @@ bool lspcon_init(struct intel_digital_port *dig_port)
>  		return false;
>  	}
>  
> -	if (!intel_dp_read_dpcd(dp)) {
> +	if (drm_dp_read_dpcd_caps(&dp->aux, dp->dpcd) != 0) {
>  		DRM_ERROR("LSPCON DPCD read failed\n");
>  		return false;
>  	}
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 0c141fc81aaa8..11649e93e5bb6 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1607,6 +1607,9 @@ static inline ssize_t drm_dp_dpcd_writeb(struct
drm_dp_aux *aux,
>  	return drm_dp_dpcd_write(aux, offset, &value, 1);
>  }
>  
> +int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
> +			  u8 dpcd[DP_RECEIVER_CAP_SIZE]);
> +
>  int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
>  				 u8 status[DP_LINK_STATUS_SIZE]);
>  
> -- 
> 2.26.2
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 
Sean Paul, Software Engineer, Google / Chromium OS