Re: [PATCH v3] drm: Guard DRM_CLIENT_CAP_PLANE_COLOR_PIPELINE

[Maarten Lankhorst]

Hey,

On 7/9/26 08:44, Borah, Chaitanya Kumar wrote:
> 
> 
> On 7/7/2026 6:31 PM, Maarten Lankhorst wrote:
>> Hey,
>>
>> On 7/7/26 10:03, Borah, Chaitanya Kumar wrote:
>>>
>>> On 7/3/2026 1:02 PM, Robert Mader wrote:
>>>> The client cap is currently advertised unconditionally, even for drivers
>>>> that do not support plane color pipelines. If clients supporting the later,
>>> s/later/latter
>>>
>>>> like Wayland compositors or tools like drm_info, enable the client cap on
>>>> such drivers they will be left without both color pipeline and the legacy
>>>> properties COLOR_ENCODING and COLOR_RANGE, effectively breaking YUV->RGB
>>>> conversion support.
>>>>
>>>> Prevent that by only marking the cap supported if there are actually planes
>>>> with color pipelines.
>>>>
>>>> Note: while the color pipeline replacement for the legacy properties is
>>>> still under review (1), we can assume that it will work as a drop-in
>>>> replacement.
>>> This change will but a driver can also choose to export colorops like programmable CTM_3x4 to achieve the same.
>>>
>>> We should also perhaps document this somewhere that if a driver supports LEGACY properties, it is imperative to implement some version of it with the color pipeline line property.
>> Would this be doable inside drm core? Implement the color pipeline properties, get the fixed pipeline for free?
> 
> Right now, the Bypass(default) pipeline is automatically created when we call drm_plane_create_color_pipeline_property(), we could come up with a similar helper that could also create a pipeline that replaces the legacy properties.
> 
> But this can't replace the existing helper entirely because some HW (though unlikely) might not support YUV buffers.

No need to do this for free, but a cheaper way for drivers to implement legacy
properties by only implementing the pipeline would be nice, similar to how
atomic also implements legacy modesetting and universal planes.

Kind regards,
~Maarten Lankhorst