On Wednesday, 19 November 2025 10:09:12 Central European Standard Time Maxime 
Ripard wrote:
> Hi,
> 
> On Mon, Nov 17, 2025 at 08:11:51PM +0100, Nicolas Frattaroli wrote:
> > With the introduction of the "color format" DRM property, which allows
> > userspace to request a specific color format, the HDMI state helper
> > should implement this.
> > 
> > Implement it by checking whether the property is set and set to
> > something other than auto. If so, pass the requested color format, and
> > otherwise set RGB.
> > 
> > Signed-off-by: Nicolas Frattaroli <[email protected]>
> > ---
> >  drivers/gpu/drm/display/drm_hdmi_state_helper.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c 
> > b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > index a561f124be99..add0d51fce33 100644
> > --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > @@ -650,9 +650,15 @@ hdmi_compute_config(const struct drm_connector 
> > *connector,
> >                                    conn_state->max_bpc,
> >                                    8, connector->max_bpc);
> >     int ret;
> > +   enum hdmi_colorspace hdmi_colorspace;
> > +
> > +   if (conn_state->color_format && conn_state->color_format != 
> > DRM_COLOR_FORMAT_AUTO)
> > +           hdmi_colorspace = 
> > color_format_to_hdmi_colorspace(conn_state->color_format);
> > +   else
> > +           hdmi_colorspace = HDMI_COLORSPACE_RGB;
> >  
> >     ret = hdmi_compute_format_bpc(connector, conn_state, mode, max_bpc,
> > -                                 HDMI_COLORSPACE_RGB);
> > +                                 hdmi_colorspace);
> 
> I don't think we want the fallback to yuv420 for anything but auto, so

Okay. Changing all the non-hdmi-state-helper drivers (amdgpu, i915)
to do this as well would require some more work however, especially
in the case of amdgpu where the code flow is not always obvious.

> I'd rather have something like
> 
> if (conn_state->color_format != DRM_COLOR_FORMAT_AUTO)
>    return hdmi_compute_format_bpc(connector, conn_state, mode, max_bpc,
>                                   
> color_format_to_hdmi_colorspace(conn_state->color_format))
> 
> We'll also need unit tests.

Sure, am I guessing correctly that they'd go in
drm_hdmi_state_helper_test.c?

> Maxime
> 




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