[PATCH v3] drm: drm_fourcc: add 10/12/16bit software decoder YCbCr formats

[Robert Mader]

Hey Dave,

sorry for the noise, I just wanted to quickly ask if with Daniels R-b 
below this patch is good to go into 6.16 once the window opens? Still 
new to the process here, therefore want to double-check :)

Thanks and best regards,

Robert Mader

On 12.05.25 16:26, Daniel Stone wrote:
> Hi Rob,
>
> On Fri, 9 May 2025 at 14:36, Robert Mader <robert.mader at collabora.com> wrote:
>> This adds FOURCCs for 3-plane 10/12/16bit YCbCr formats used by software
>> decoders like ffmpeg, dav1d and libvpx. The intended use-case is buffer
>> sharing between decoders and GPUs by allocating buffers with e.g. udmabuf
>> or dma-heaps, avoiding unnecessary copies and format conversions in
>> various scenarios.
>>
>> Unlike formats typically used by hardware decoders the 10/12bit formats
>> use a LSB alignment. In order to allow fast implementations in GL
>> and Vulkan the padding must contain only zeros, so the float
>> representation can be calculated by multiplying with 2^6=64 or 2^4=16
>> respectively.
>>
>> MRs or branches for Mesa, Vulkan, Gstreamer, Weston and Mutter can be found at:
>>   - https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34303
>>   - https://github.com/rmader/Vulkan-Docs/commits/ycbcr-16bit-lsb-formats/
>>   - https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8540
>>   - https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/1753
>>   - https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4348
>>
>> The naming scheme follows the 'P' and 'Q' formats. The 'S' stands for
>> 'software' and was selected in order to make remembering easy.
>>
>> The 'Sx16' formats could as well be 'Qx16'. We stick with 'S' as 16bit software
>> decoders are likely much more common than hardware ones for the foreseeable
>> future. Note that these formats already have Vulkan equivalents:
>>   - VK_FORMAT_G16_B16_R16_3PLANE_420_UNORM
>>   - VK_FORMAT_G16_B16_R16_3PLANE_422_UNORM
>>   - VK_FORMAT_G16_B16_R16_3PLANE_444_UNORM
> Thanks a lot for these - series is:
> Reviewed-by: Daniel Stone <daniels at collabora.com>
>
> Cheers,
> Daniel