Nouveau - Sep 2018 - [PATCH 3/6] drm/i915: Leave intel_conn->mst_port set, use mst_port_gone instead

Currently we set intel_connector->mst_port to NULL to signify that the
MST port has been removed from the system so that we can prevent further
action on the port such as connector probes, mode probing, etc.
However, we're going to need access to intel_connector->mst_port in
order to fixup ->best_encoder() so that it can always return the correct
encoder for an MST port to prevent legacy DPMS prop changes from
failing. This should be safe, so instead keep intel_connector->mst_port
always set and instead add intel_connector->mst_port_gone in order to
signify whether or not the connector has disappeared from the system.

Signed-off-by: Lyude Paul <lyude at redhat.com>
Cc: stable at vger.kernel.org
---
 drivers/gpu/drm/i915/intel_dp_mst.c | 14 +++++++-------
 drivers/gpu/drm/i915/intel_drv.h    |  1 +
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c
b/drivers/gpu/drm/i915/intel_dp_mst.c
index 4ecd65375603..fcb9b87b9339 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -311,9 +311,8 @@ static int intel_dp_mst_get_ddc_modes(struct drm_connector
*connector)
 	struct edid *edid;
 	int ret;
 
-	if (!intel_dp) {
+	if (intel_connector->mst_port_gone)
 		return intel_connector_update_modes(connector, NULL);
-	}
 
 	edid = drm_dp_mst_get_edid(connector, &intel_dp->mst_mgr,
intel_connector->port);
 	ret = intel_connector_update_modes(connector, edid);
@@ -328,9 +327,10 @@ intel_dp_mst_detect(struct drm_connector *connector, bool
force)
 	struct intel_connector *intel_connector = to_intel_connector(connector);
 	struct intel_dp *intel_dp = intel_connector->mst_port;
 
-	if (!intel_dp)
+	if (intel_connector->mst_port_gone)
 		return connector_status_disconnected;
-	return drm_dp_mst_detect_port(connector, &intel_dp->mst_mgr,
intel_connector->port);
+	return drm_dp_mst_detect_port(connector, &intel_dp->mst_mgr,
+				      intel_connector->port);
 }
 
 static void
@@ -370,7 +370,7 @@ intel_dp_mst_mode_valid(struct drm_connector *connector,
 	int bpp = 24; /* MST uses fixed bpp */
 	int max_rate, mode_rate, max_lanes, max_link_clock;
 
-	if (!intel_dp)
+	if (intel_connector->mst_port_gone)
 		return MODE_ERROR;
 
 	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
@@ -402,7 +402,7 @@ static struct drm_encoder
*intel_mst_atomic_best_encoder(struct drm_connector *c
 	struct intel_dp *intel_dp = intel_connector->mst_port;
 	struct intel_crtc *crtc = to_intel_crtc(state->crtc);
 
-	if (!intel_dp)
+	if (intel_connector->mst_port_gone)
 		return NULL;
 	return &intel_dp->mst_encoders[crtc->pipe]->base.base;
 }
@@ -514,7 +514,7 @@ static void intel_dp_destroy_mst_connector(struct
drm_dp_mst_topology_mgr *mgr,
 						   connector);
 	/* prevent race with the check in ->detect */
 	drm_modeset_lock(&connector->dev->mode_config.connection_mutex,
NULL);
-	intel_connector->mst_port = NULL;
+	intel_connector->mst_port_gone = true;
 	drm_modeset_unlock(&connector->dev->mode_config.connection_mutex);
 
 	drm_connector_put(connector);
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 8fc61e96754f..87ce772ae7f8 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -409,6 +409,7 @@ struct intel_connector {
 	void *port; /* store this opaque as its illegal to dereference it */
 
 	struct intel_dp *mst_port;
+	bool mst_port_gone;
 
 	/* Work struct to schedule a uevent on link train failure */
 	struct work_struct modeset_retry_work;
-- 
2.17.1

Hi,

[This is an automated email]

This commit has been processed because it contains a -stable tag.
The stable tag indicates that it's relevant for the following trees: all

The bot has tested the following trees: v4.18.8, v4.14.70, v4.9.127, v4.4.156,
v3.18.122,

v4.18.8: Build OK!
v4.14.70: Build OK!
v4.9.127: Failed to apply! Possible dependencies:
    06bfe5b0d892 ("drm/i915: Avoid null dereference if mst_port is
unset.")
    22a2c8e0457f ("drm/i915: Validate mode against max. link data rate for
DP MST")
    9301397a63b3 ("drm/i915: Implement Link Rate fallback on Link training
failure")
    af2405af07d1 ("drm/fb-helper: Push down modeset lock into FB
helpers")

v4.4.156: Failed to apply! Possible dependencies:
    0552f7651bc2 ("drm/i915/mst: use reference counted connectors.
(v3)")
    06bfe5b0d892 ("drm/i915: Avoid null dereference if mst_port is
unset.")
    22a2c8e0457f ("drm/i915: Validate mode against max. link data rate for
DP MST")
    9301397a63b3 ("drm/i915: Implement Link Rate fallback on Link training
failure")
    af2405af07d1 ("drm/fb-helper: Push down modeset lock into FB
helpers")

v3.18.122: Failed to apply! Possible dependencies:
    0552f7651bc2 ("drm/i915/mst: use reference counted connectors.
(v3)")
    06bfe5b0d892 ("drm/i915: Avoid null dereference if mst_port is
unset.")
    22a2c8e0457f ("drm/i915: Validate mode against max. link data rate for
DP MST")
    459485ad3513 ("drm/i915: Fixup dp mst encoder selection")
    9301397a63b3 ("drm/i915: Implement Link Rate fallback on Link training
failure")
    af2405af07d1 ("drm/fb-helper: Push down modeset lock into FB
helpers")
    c6a0aed4d493 ("drm/mst: cached EDID for logical ports (v2)")


Please let us know how to resolve this.

--
Thanks,
Sasha

On Wed, 2018-09-19 at 18:58 +0000, Sasha Levin wrote:
> Hi,
> 
> [This is an automated email]
> 
> This commit has been processed because it contains a -stable tag.
> The stable tag indicates that it's relevant for the following trees:
all
> 
> The bot has tested the following trees: v4.18.8, v4.14.70, v4.9.127,
v4.4.156,
> v3.18.122, 
> 
> v4.18.8: Build OK!
> v4.14.70: Build OK!
> v4.9.127: Failed to apply! Possible dependencies:
>     06bfe5b0d892 ("drm/i915: Avoid null dereference if mst_port is
unset.")
>     22a2c8e0457f ("drm/i915: Validate mode against max. link data rate
for DP
> MST")
>     9301397a63b3 ("drm/i915: Implement Link Rate fallback on Link
training
> failure")
>     af2405af07d1 ("drm/fb-helper: Push down modeset lock into FB
helpers")
> 
> v4.4.156: Failed to apply! Possible dependencies:
>     0552f7651bc2 ("drm/i915/mst: use reference counted connectors.
(v3)")
>     06bfe5b0d892 ("drm/i915: Avoid null dereference if mst_port is
unset.")
>     22a2c8e0457f ("drm/i915: Validate mode against max. link data rate
for DP
> MST")
>     9301397a63b3 ("drm/i915: Implement Link Rate fallback on Link
training
> failure")
>     af2405af07d1 ("drm/fb-helper: Push down modeset lock into FB
helpers")
> 
> v3.18.122: Failed to apply! Possible dependencies:
>     0552f7651bc2 ("drm/i915/mst: use reference counted connectors.
(v3)")
>     06bfe5b0d892 ("drm/i915: Avoid null dereference if mst_port is
unset.")
>     22a2c8e0457f ("drm/i915: Validate mode against max. link data rate
for DP
> MST")
>     459485ad3513 ("drm/i915: Fixup dp mst encoder selection")
>     9301397a63b3 ("drm/i915: Implement Link Rate fallback on Link
training
> failure")
>     af2405af07d1 ("drm/fb-helper: Push down modeset lock into FB
helpers")
>     c6a0aed4d493 ("drm/mst: cached EDID for logical ports (v2)")
> 
> 
> Please let us know how to resolve this.
...is this the email address I'm supposed to "let you know how to
resolve this"
with? if that is the case, it's 100% OK to simply ignore all of the versions
that don't apply with this patch.
> 
> --
> Thanks,
> Sasha

On Tue, Sep 18, 2018 at 07:06:19PM -0400, Lyude Paul
wrote:
> Currently we set intel_connector->mst_port to NULL to signify that the
> MST port has been removed from the system so that we can prevent further
> action on the port such as connector probes, mode probing, etc.
> However, we're going to need access to intel_connector->mst_port in
> order to fixup ->best_encoder() so that it can always return the correct
> encoder for an MST port to prevent legacy DPMS prop changes from
> failing. This should be safe, so instead keep intel_connector->mst_port
> always set and instead add intel_connector->mst_port_gone in order to
> signify whether or not the connector has disappeared from the system.
> 
> Signed-off-by: Lyude Paul <lyude at redhat.com>
> Cc: stable at vger.kernel.org
Hm, how exactly do legacy DPMS setprop blow up here? Or at least I can't
come up with a scenario that's specific to legacy props, atomic should be
equally affected. By the time we land in this code, the core code already
remapping it to be purely an atomic update.

Another thought: Should we handle at least some of this in the probe
helpers? I.e. once you unplugged a drm_connector, it always shows
disconnected and mode list is gone, instead of duplicating this over all
drivers. We could just check connector->registered.

Thanks, Daniel
> ---
>  drivers/gpu/drm/i915/intel_dp_mst.c | 14 +++++++-------
>  drivers/gpu/drm/i915/intel_drv.h    |  1 +
>  2 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c
b/drivers/gpu/drm/i915/intel_dp_mst.c
> index 4ecd65375603..fcb9b87b9339 100644
> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> @@ -311,9 +311,8 @@ static int intel_dp_mst_get_ddc_modes(struct
drm_connector *connector)
>  	struct edid *edid;
>  	int ret;
>  
> -	if (!intel_dp) {
> +	if (intel_connector->mst_port_gone)
>  		return intel_connector_update_modes(connector, NULL);
> -	}
>  
>  	edid = drm_dp_mst_get_edid(connector, &intel_dp->mst_mgr,
intel_connector->port);
>  	ret = intel_connector_update_modes(connector, edid);
> @@ -328,9 +327,10 @@ intel_dp_mst_detect(struct drm_connector *connector,
bool force)
>  	struct intel_connector *intel_connector = to_intel_connector(connector);
>  	struct intel_dp *intel_dp = intel_connector->mst_port;
>  
> -	if (!intel_dp)
> +	if (intel_connector->mst_port_gone)
>  		return connector_status_disconnected;
> -	return drm_dp_mst_detect_port(connector, &intel_dp->mst_mgr,
intel_connector->port);
> +	return drm_dp_mst_detect_port(connector, &intel_dp->mst_mgr,
> +				      intel_connector->port);
>  }
>  
>  static void
> @@ -370,7 +370,7 @@ intel_dp_mst_mode_valid(struct drm_connector
*connector,
>  	int bpp = 24; /* MST uses fixed bpp */
>  	int max_rate, mode_rate, max_lanes, max_link_clock;
>  
> -	if (!intel_dp)
> +	if (intel_connector->mst_port_gone)
>  		return MODE_ERROR;
>  
>  	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
> @@ -402,7 +402,7 @@ static struct drm_encoder
*intel_mst_atomic_best_encoder(struct drm_connector *c
>  	struct intel_dp *intel_dp = intel_connector->mst_port;
>  	struct intel_crtc *crtc = to_intel_crtc(state->crtc);
>  
> -	if (!intel_dp)
> +	if (intel_connector->mst_port_gone)
>  		return NULL;
>  	return &intel_dp->mst_encoders[crtc->pipe]->base.base;
>  }
> @@ -514,7 +514,7 @@ static void intel_dp_destroy_mst_connector(struct
drm_dp_mst_topology_mgr *mgr,
>  						   connector);
>  	/* prevent race with the check in ->detect */
>  	drm_modeset_lock(&connector->dev->mode_config.connection_mutex,
NULL);
> -	intel_connector->mst_port = NULL;
> +	intel_connector->mst_port_gone = true;
>  
drm_modeset_unlock(&connector->dev->mode_config.connection_mutex);
>  
>  	drm_connector_put(connector);
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
b/drivers/gpu/drm/i915/intel_drv.h
> index 8fc61e96754f..87ce772ae7f8 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -409,6 +409,7 @@ struct intel_connector {
>  	void *port; /* store this opaque as its illegal to dereference it */
>  
>  	struct intel_dp *mst_port;
> +	bool mst_port_gone;
>  
>  	/* Work struct to schedule a uevent on link train failure */
>  	struct work_struct modeset_retry_work;
> -- 
> 2.17.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

On Fri, 2018-09-21 at 11:27 +0200, Daniel Vetter wrote:
> On Tue, Sep 18, 2018 at 07:06:19PM -0400, Lyude Paul wrote:
> > Currently we set intel_connector->mst_port to NULL to signify that
the
> > MST port has been removed from the system so that we can prevent
further
> > action on the port such as connector probes, mode probing, etc.
> > However, we're going to need access to
intel_connector->mst_port in
> > order to fixup ->best_encoder() so that it can always return the
correct
> > encoder for an MST port to prevent legacy DPMS prop changes from
> > failing. This should be safe, so instead keep
intel_connector->mst_port
> > always set and instead add intel_connector->mst_port_gone in order
to
> > signify whether or not the connector has disappeared from the system.
> > 
> > Signed-off-by: Lyude Paul <lyude at redhat.com>
> > Cc: stable at vger.kernel.org
> 
> Hm, how exactly do legacy DPMS setprop blow up here? Or at least I
can't
> come up with a scenario that's specific to legacy props, atomic should
be
> equally affected. By the time we land in this code, the core code already
> remapping it to be purely an atomic update.
So, what I've been seeing with X that's been blowing this up:
 * Hotplug event gets received, X does reprobe
 * Notices MST connectors are now disconnected, sets DPMS from on->off
 * During atomic_check, drm_atomic_helper_check_modeset() is called
 * update_connector_routing() gets called
 * funcs->best_encoder() returns NULL for the encoder
 * update_connector_routing() fails atomic commit with "No suitable encoder
   found", line 320 of drm_atomic_helper
> 
> Another thought: Should we handle at least some of this in the probe
> helpers? I.e. once you unplugged a drm_connector, it always shows
> disconnected and mode list is gone, instead of duplicating this over all
> drivers. We could just check connector->registered.
oooh, good idea! I will certainly go do that
> 
> Thanks, Daniel
> > ---
> >  drivers/gpu/drm/i915/intel_dp_mst.c | 14 +++++++-------
> >  drivers/gpu/drm/i915/intel_drv.h    |  1 +
> >  2 files changed, 8 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c
> > b/drivers/gpu/drm/i915/intel_dp_mst.c
> > index 4ecd65375603..fcb9b87b9339 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > @@ -311,9 +311,8 @@ static int intel_dp_mst_get_ddc_modes(struct
> > drm_connector *connector)
> >  	struct edid *edid;
> >  	int ret;
> >  
> > -	if (!intel_dp) {
> > +	if (intel_connector->mst_port_gone)
> >  		return intel_connector_update_modes(connector, NULL);
> > -	}
> >  
> >  	edid = drm_dp_mst_get_edid(connector, &intel_dp->mst_mgr,
> > intel_connector->port);
> >  	ret = intel_connector_update_modes(connector, edid);
> > @@ -328,9 +327,10 @@ intel_dp_mst_detect(struct drm_connector
*connector,
> > bool force)
> >  	struct intel_connector *intel_connector > >
to_intel_connector(connector);
> >  	struct intel_dp *intel_dp = intel_connector->mst_port;
> >  
> > -	if (!intel_dp)
> > +	if (intel_connector->mst_port_gone)
> >  		return connector_status_disconnected;
> > -	return drm_dp_mst_detect_port(connector, &intel_dp->mst_mgr,
> > intel_connector->port);
> > +	return drm_dp_mst_detect_port(connector, &intel_dp->mst_mgr,
> > +				      intel_connector->port);
> >  }
> >  
> >  static void
> > @@ -370,7 +370,7 @@ intel_dp_mst_mode_valid(struct drm_connector
> > *connector,
> >  	int bpp = 24; /* MST uses fixed bpp */
> >  	int max_rate, mode_rate, max_lanes, max_link_clock;
> >  
> > -	if (!intel_dp)
> > +	if (intel_connector->mst_port_gone)
> >  		return MODE_ERROR;
> >  
> >  	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
> > @@ -402,7 +402,7 @@ static struct drm_encoder
> > *intel_mst_atomic_best_encoder(struct drm_connector *c
> >  	struct intel_dp *intel_dp = intel_connector->mst_port;
> >  	struct intel_crtc *crtc = to_intel_crtc(state->crtc);
> >  
> > -	if (!intel_dp)
> > +	if (intel_connector->mst_port_gone)
> >  		return NULL;
> >  	return &intel_dp->mst_encoders[crtc->pipe]->base.base;
> >  }
> > @@ -514,7 +514,7 @@ static void intel_dp_destroy_mst_connector(struct
> > drm_dp_mst_topology_mgr *mgr,
> >  						   connector);
> >  	/* prevent race with the check in ->detect */
> >  
drm_modeset_lock(&connector->dev->mode_config.connection_mutex, NULL);
> > -	intel_connector->mst_port = NULL;
> > +	intel_connector->mst_port_gone = true;
> >  
drm_modeset_unlock(&connector->dev->mode_config.connection_mutex);
> >  
> >  	drm_connector_put(connector);
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > b/drivers/gpu/drm/i915/intel_drv.h
> > index 8fc61e96754f..87ce772ae7f8 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -409,6 +409,7 @@ struct intel_connector {
> >  	void *port; /* store this opaque as its illegal to dereference it */
> >  
> >  	struct intel_dp *mst_port;
> > +	bool mst_port_gone;
> >  
> >  	/* Work struct to schedule a uevent on link train failure */
> >  	struct work_struct modeset_retry_work;
> > -- 
> > 2.17.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> 
-- 
Cheers,
	Lyude Paul