Re: [PATCH v4 07/10] drm/display: hdmi-state-helper: Act on color format DRM property

[Maxime Ripard]

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 <nicolas.frattar...@collabora.com>
> ---
>  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
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.

Maxime

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