Nouveau - Aug 2019 - [PATCH v3 5/7] drm/nouveau: utilize subconnector property for DP

On Mon, Aug 26, 2019 at 09:36:50AM -0400, Ilia Mirkin
wrote:
> This should probably be fixed to account for the scenario where an
> HDMI connector is plugged directly into the DP++ port. I don't think
> the dp.subconnector property will be valid in that case.
> (Unfortunately I don't remember how one detects that particular
> situation.)
One may or may not be able to detect it very well. I've seen dongles
that automagically change the DFP type from DP++ to DP/HDMI depending
on what's plugged in, and I've also seen dongles that leave the DFP
type to DP++.

I'm actually broiling a series of patches which try to improve how
i915 handles various DFP types, and for that I'm thinking of using
a combination of the DFP type and the EDID digital input type to
differentiate between the two cases like so:

static bool is_edid_digital_input_dp(const struct edid *edid)
{
	return edid && edid->revision >= 4 &&
		edid->input & DRM_EDID_INPUT_DIGITAL &&
		(edid->input & DRM_EDID_DIGITAL_TYPE_MASK) == DRM_EDID_DIGITAL_TYPE_DP;
}

{
	switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
	case DP_DS_PORT_TYPE_DP:
		DP_STUFF;
	case DP_DS_PORT_TYPE_DP_DUALMODE:
		if (is_edid_digital_input_dp(edid))
			DP_STUFF;
		/* fall through */
	case DP_DS_PORT_TYPE_HDMI:
	case DP_DS_PORT_TYPE_DVI:
		TMDS_STUFF;
}
> 
> On Mon, Aug 26, 2019 at 9:22 AM Oleg Vasilev <oleg.vasilev at
intel.com> wrote:
> >
> > Since DP-specific information is stored in driver's structures,
every
> > driver needs to implement subconnector property by itself.
> >
> > Reviewed-by: Emil Velikov <emil.velikov at collabora.com>
> > Signed-off-by: Oleg Vasilev <oleg.vasilev at intel.com>
> > Cc: Ben Skeggs <bskeggs at redhat.com>
> > Cc: nouveau at lists.freedesktop.org
> > ---
> >  drivers/gpu/drm/nouveau/nouveau_connector.c | 13 +++++++++++++
> >  drivers/gpu/drm/nouveau/nouveau_dp.c        |  9 +++++++++
> >  drivers/gpu/drm/nouveau/nouveau_encoder.h   |  1 +
> >  3 files changed, 23 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c
b/drivers/gpu/drm/nouveau/nouveau_connector.c
> > index 94dfa2e5a9ab..d9c116cc11b9 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
> > @@ -635,6 +635,17 @@ nouveau_connector_detect(struct drm_connector
*connector, bool force)
> >         pm_runtime_mark_last_busy(dev->dev);
> >         pm_runtime_put_autosuspend(dev->dev);
> >
> > +       if (connector->connector_type ==
DRM_MODE_CONNECTOR_DisplayPort ||
> > +           connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> > +               enum drm_mode_subconnector subconnector =
DRM_MODE_SUBCONNECTOR_Unknown;
> > +
> > +               if (conn_status == connector_status_connected
&& nv_encoder)
> > +                       subconnector = nv_encoder->dp.subconnector;
> > +               drm_object_property_set_value(&connector->base,
> > +                      
connector->dev->mode_config.dp_subconnector_property,
> > +                       subconnector);
> > +       }
> > +
> >         return conn_status;
> >  }
> >
> > @@ -1359,6 +1370,8 @@ nouveau_connector_create(struct drm_device *dev,
> >                         kfree(nv_connector);
> >                         return ERR_PTR(ret);
> >                 }
> > +
> > +               drm_mode_add_dp_subconnector_property(connector);
> >                 funcs = &nouveau_connector_funcs;
> >                 break;
> >         default:
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c
b/drivers/gpu/drm/nouveau/nouveau_dp.c
> > index 2674f1587457..85eac853e3f8 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_dp.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
> > @@ -62,6 +62,7 @@ nouveau_dp_detect(struct nouveau_encoder
*nv_encoder)
> >         struct nouveau_drm *drm = nouveau_drm(dev);
> >         struct nvkm_i2c_aux *aux;
> >         u8 dpcd[8];
> > +       u8 port_cap[DP_MAX_DOWNSTREAM_PORTS] = {};
> >         int ret;
> >
> >         aux = nv_encoder->aux;
> > @@ -72,6 +73,14 @@ nouveau_dp_detect(struct nouveau_encoder
*nv_encoder)
> >         if (ret)
> >                 return ret;
> >
> > +       if (dpcd[DP_DPCD_REV] > 0x10) {
> > +               ret = nvkm_rdaux(aux, DP_DOWNSTREAM_PORT_0,
> > +                                port_cap, DP_MAX_DOWNSTREAM_PORTS);
> > +               if (ret)
> > +                       memset(port_cap, 0, DP_MAX_DOWNSTREAM_PORTS);
> > +       }
> > +       nv_encoder->dp.subconnector =
drm_dp_subconnector_type(dpcd, port_cap);
> > +
> >         nv_encoder->dp.link_bw = 27000 * dpcd[1];
> >         nv_encoder->dp.link_nr = dpcd[2] &
DP_MAX_LANE_COUNT_MASK;
> >
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h
b/drivers/gpu/drm/nouveau/nouveau_encoder.h
> > index 3517f920bf89..e17971a30221 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
> > +++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
> > @@ -63,6 +63,7 @@ struct nouveau_encoder {
> >                         struct nv50_mstm *mstm;
> >                         int link_nr;
> >                         int link_bw;
> > +                       enum drm_mode_subconnector subconnector;
> >                 } dp;
> >         };
> >
> > --
> > 2.23.0
> >
> > _______________________________________________
> > Nouveau mailing list
> > Nouveau at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/nouveau
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 
Ville Syrjälä
Intel

On Wed, Aug 28, 2019 at 10:38 AM Ville Syrjälä
<ville.syrjala at linux.intel.com> wrote:
>
> On Mon, Aug 26, 2019 at 09:36:50AM -0400, Ilia Mirkin wrote:
> > This should probably be fixed to account for the scenario where an
> > HDMI connector is plugged directly into the DP++ port. I don't
think
> > the dp.subconnector property will be valid in that case.
> > (Unfortunately I don't remember how one detects that particular
> > situation.)
>
> One may or may not be able to detect it very well. I've seen dongles
> that automagically change the DFP type from DP++ to DP/HDMI depending
> on what's plugged in, and I've also seen dongles that leave the DFP
> type to DP++.
Well, our internal logic certainly knows if it's driving DP or TMDS. I
just don't remember how it knows this.

  -ilia

On Wed, Aug 28, 2019 at 10:47:08AM -0400, Ilia Mirkin
wrote:
> On Wed, Aug 28, 2019 at 10:38 AM Ville Syrjälä
> <ville.syrjala at linux.intel.com> wrote:
> >
> > On Mon, Aug 26, 2019 at 09:36:50AM -0400, Ilia Mirkin wrote:
> > > This should probably be fixed to account for the scenario where
an
> > > HDMI connector is plugged directly into the DP++ port. I
don't think
> > > the dp.subconnector property will be valid in that case.
> > > (Unfortunately I don't remember how one detects that
particular
> > > situation.)
> >
> > One may or may not be able to detect it very well. I've seen
dongles
> > that automagically change the DFP type from DP++ to DP/HDMI depending
> > on what's plugged in, and I've also seen dongles that leave
the DFP
> > type to DP++.
> 
> Well, our internal logic certainly knows if it's driving DP or TMDS. I
> just don't remember how it knows this.
You'll be driving DP in this case. The DFP will be the one driving
DP or TMDS depending on what's plugged in.

-- 
Ville Syrjälä
Intel