Pi 0-3 have no deep colour support and only 24bpp output,
so max_bpc should remain as 8, and no HDR metadata property
should be registered.

Fixes: ba8c0faebbb0 ("drm/vc4: hdmi: Enable 10/12 bpc output")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 62b82b1eeb36..6ebcc38be291 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -640,6 +640,11 @@ static int vc4_hdmi_connector_init(struct drm_device *dev,
 	if (ret)
 		return ret;
 
+	if (vc4_hdmi->variant->supports_hdr)
+		drm_connector_attach_max_bpc_property(connector, 8, 12);
+	else
+		drm_connector_attach_max_bpc_property(connector, 8, 8);
+
 	drm_connector_attach_encoder(connector, encoder);
 
 	return 0;

-- 
2.34.1

On Wed, Oct 23, 2024 at 05:49:58PM +0100, Dave Stevenson wrote:
> Pi 0-3 have no deep colour support and only 24bpp output,
> so max_bpc should remain as 8, and no HDR metadata property
> should be registered.
> 
> Fixes: ba8c0faebbb0 ("drm/vc4: hdmi: Enable 10/12 bpc output")
> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 62b82b1eeb36..6ebcc38be291 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -640,6 +640,11 @@ static int vc4_hdmi_connector_init(struct drm_device *dev,
>  	if (ret)
>  		return ret;
>  
> +	if (vc4_hdmi->variant->supports_hdr)
> +		drm_connector_attach_max_bpc_property(connector, 8, 12);
> +	else
> +		drm_connector_attach_max_bpc_property(connector, 8, 8);
> +

Are you sure that one is needed?

https://elixir.bootlin.com/linux/v6.11.5/source/drivers/gpu/drm/vc4/vc4_hdmi.c#L594
should take care about all that already.

Maxime