Re: [PATCH v3] drm: Guard DRM_CLIENT_CAP_PLANE_COLOR_PIPELINE

[Robert Mader <robert.mader@collabora.com>]

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Hi Harry,

On 21.07.26 15:55, Harry Wentland wrote:
>>> ...
>> If I understand you correctly you suggest to map legacy COLOR_RANGE and COLOR_ENCODING to the new FIXED_MATRIX colorop in a generic way, instead of having drivers advertise them separately. Do I have that right?
>>
>> It's probably a good idea. It should be easy to make that change after merging the Fixed Matrix series with YUV support.
>>
> I sketched this out but both VKMS and amdgpu have HW generations
> or configs where no color pipeline is created. For that we still
> need the current way of COLOR_RANGE and COLOR_ENCODING handling.
> Because of this the code to create COLOR_RANGE and COLOR_ENCODING
> based on the color pipeline is not really simplifying things, but
> merely adding more code.
>
> At this point I am not convinced adding helpers to create COLOR_RANGE
> and COLOR_ENCODING based on the color pipeline is a net positive.
> Maybe in the future that equation changes.
>
> If anyone is interested I'm still happy to share the code. Just
> let me know.
>
> Harry

thanks for taking a look! I'd be very interested - mainly because in my 
understanding the "both VKMS and amdgpu have HW generations or configs 
where no color pipeline is created" should be fixable:

 1. For amdgpu every hardware generation supporting COLOR_RANGE and
    COLOR_ENCODING should be able to create a color pipeline *only*
    exposing the corresponding FIXED_MATRIX colorop, mapping to the
    exact same hardware block internally. I hope that shouldn't conflict
    too much with the current architecture?
 2. In case of VKMS the "enable_plane_pipeline" config could be adopted
    so that - if it is disabled - the plane pipeline is still
    initialized but only the FIXED_MATRIX colorop is added. Additionally
    we would need to disable DRM_CLIENT_CAP_PLANE_COLOR_PIPELINE -
    possibly by a driver cap similar to v1 of this series - so that
    userspace can't enable/use the colop-op directly. As a result, VKMS
    with enable_plane_pipeline=0 should get the legacy properties via
    your helper, be able to drop explicit handling of them.

Does that make sense / do you think that could work?

Best regards,

Robert

-- 
Robert Mader
Consultant Software Developer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
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