Re: [PATCH v3 09/17] drm/amd/display: Register Colorspace property for DP and HDMI

[Pekka Paalanen <ppaalanen@gmail.com>]

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On Thu, 16 Mar 2023 11:50:27 +0200
Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:

> On Thu, Mar 16, 2023 at 01:37:24AM +0100, Sebastian Wick wrote:
> > On Tue, Mar 7, 2023 at 4:12 PM Harry Wentland <harry.wentland@amd.com> wrote:  
> > >
> > > We want compositors to be able to set the output
> > > colorspace on DP and HDMI outputs, based on the
> > > caps reported from the receiver via EDID.  
> > 
> > About that... The documentation says that user space has to check the
> > EDID for what the sink actually supports. So whatever is in
> > supported_colorspaces is just what the driver/hardware is able to set
> > but doesn't actually indicate that the sink supports it.
> > 
> > So the only way to enable bt2020 is by checking if the sink supports
> > both RGB and YUV variants because both could be used by the driver.
> > Not great at all. Something to remember for the new property.  
> 
> Hmm. I wonder if that's even legal... Looks like maybe it
> is since I can't immediately spot anything in CTA-861 to
> forbid it :/

Wouldn't the driver do the same EDID check before choosing whether it
uses RGB or YCbCr signalling?

So if EDID says only one of them is supported, userspace should be
confident that that is the BT2020 mode the driver will match?


Thanks,
pq

> 
> >   
> > > Signed-off-by: Harry Wentland <harry.wentland@amd.com>
> > > Cc: Pekka Paalanen <ppaalanen@gmail.com>
> > > Cc: Sebastian Wick <sebastian.wick@redhat.com>
> > > Cc: Vitaly.Prosyak@amd.com
> > > Cc: Joshua Ashton <joshua@froggi.es>
> > > Cc: dri-devel@lists.freedesktop.org
> > > Cc: amd-gfx@lists.freedesktop.org
> > > Reviewed-By: Joshua Ashton <joshua@froggi.es>
> > > ---
> > >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 15 +++++++++++++++
> > >  1 file changed, 15 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > index f91b2ea13d96..2d883c6dae90 100644
> > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > > @@ -7184,6 +7184,12 @@ static int amdgpu_dm_connector_get_modes(struct drm_connector *connector)
> > >         return amdgpu_dm_connector->num_modes;
> > >  }
> > >
> > > +static const u32 supported_colorspaces =
> > > +       BIT(DRM_MODE_COLORIMETRY_BT709_YCC) |
> > > +       BIT(DRM_MODE_COLORIMETRY_OPRGB) |
> > > +       BIT(DRM_MODE_COLORIMETRY_BT2020) |
> > > +       BIT(DRM_MODE_COLORIMETRY_BT2020_DEPRECATED);
> > > +
> > >  void amdgpu_dm_connector_init_helper(struct amdgpu_display_manager *dm,
> > >                                      struct amdgpu_dm_connector *aconnector,
> > >                                      int connector_type,
> > > @@ -7264,6 +7270,15 @@ void amdgpu_dm_connector_init_helper(struct amdgpu_display_manager *dm,
> > >                                 adev->mode_info.abm_level_property, 0);
> > >         }
> > >
> > > +       if (connector_type == DRM_MODE_CONNECTOR_HDMIA) {
> > > +               if (!drm_mode_create_hdmi_colorspace_property(&aconnector->base, supported_colorspaces))
> > > +                       drm_connector_attach_colorspace_property(&aconnector->base);
> > > +       } else if (connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> > > +                  connector_type == DRM_MODE_CONNECTOR_eDP) {
> > > +               if (!drm_mode_create_dp_colorspace_property(&aconnector->base, supported_colorspaces))
> > > +                       drm_connector_attach_colorspace_property(&aconnector->base);
> > > +       }
> > > +
> > >         if (connector_type == DRM_MODE_CONNECTOR_HDMIA ||
> > >             connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> > >             connector_type == DRM_MODE_CONNECTOR_eDP) {
> > > --
> > > 2.39.2
> > >  
> 


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