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Message-ID: <9e6ed0e5-c9aa-4fb9-a6d8-4c3b1d658ef2@riseup.net>
Date: Wed, 28 Feb 2024 20:42:41 -0300
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Subject: Re: [PATCH v2 0/7] Add YUV formats to VKMS
To: Sebastian Wick <sebastian.wick@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@gmail.com>,
 Haneen Mohammed <hamohammed.sa@gmail.com>,
 Harry Wentland <harry.wentland@amd.com>, Jonathan Corbet <corbet@lwn.net>,
 Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
 Maxime Ripard <mripard@kernel.org>, =?UTF-8?Q?Ma=C3=ADra_Canal?=
 <mairacanal@riseup.net>, Melissa Wen <melissa.srw@gmail.com>,
 Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
 Thomas Zimmermann <tzimmermann@suse.de>, linux-kernel@vger.kernel.org,
 dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org
References: <20240110-vkms-yuv-v2-0-952fcaa5a193@riseup.net>
 <20240115150600.GC160656@toolbox>
Content-Language: en-US
From: Arthur Grillo <arthurgrillo@riseup.net>
In-Reply-To: <20240115150600.GC160656@toolbox>
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On 15/01/24 12:06, Sebastian Wick wrote:
> On Wed, Jan 10, 2024 at 02:44:00PM -0300, Arthur Grillo wrote:
>> This patchset aims to add support for additional buffer YUV formats.
>> More specifically, it adds support to:
>>
>> Semi-planar formats:
>>
>> - NV12
>> - NV16
>> - NV24
>> - NV21
>> - NV61
>> - NV42
>>
>> Planar formats:
>>
>> - YUV440
>> - YUV422
>> - YUV444
>> - YVU440
>> - YVU422
>> - YVU444
>>
>> These formats have more than one plane, and most have chroma
>> subsampling. These properties don't have support on VKMS, so I had to
>> work on this before.
>>
>> To ensure that the conversions from YUV to RGB are working, I wrote a
>> KUnit test. As the work from Harry on creating KUnit tests on VKMS[1] is
>> not yet merged, I took the setup part (Kconfig entry and .kunitfile)
>> from it.
>>
>> Furthermore, I couldn't find any sources with the conversion matrices,
>> so I had to work out the values myself based on the ITU papers[2][3][4].
>> So, I'm not 100% sure if the values are accurate. I'd appreciate some
>> input if anyone has more knowledge in this area.
> 
> H.273 CICP [1] has concise descriptions of the required values for most
> widely used formats and the colour python framework [2] also can be used
> to quickly get to the desired information most of the time.
> 
> [1]: https://www.itu.int/rec/T-REC-H.273
> [2]: https://www.colour-science.org/

I want to thank you for suggesting the python framework, it helped
immensely now that I'm changing the precision from 8-bit to 32-bit[1].

If I'd known about this framework while developing this patch, I
would've saved myself a few weeks of pain and suffering recreating a
part of this library XD.

[1]: https://lore.kernel.org/all/b23da076-0bfb-48b2-9386-383a6dec1868@riseup.net/

Best Regards,
~Arthur Grillo

> 
>> Also, I used two IGT tests to check if the formats were having a correct
>> conversion (all with the --extended flag):
>>
>> - kms_plane@pixel_format
>> - kms_plane@pixel_format_source_clamping.
>>
>> The nonsubsampled formats don't have support on IGT, so I sent a patch
>> fixing this[5].
>>
>> Currently, this patchset does not add those formats to the writeback, as
>> it would require a rewrite of how the conversions are done (similar to
>> what was done on a previous patch[6]). So, I would like to review this
>> patchset before I start the work on this other part.
>>
>> [1]: https://lore.kernel.org/all/20231108163647.106853-5-harry.wentland@amd.com/
>> [2]: https://www.itu.int/rec/R-REC-BT.601-7-201103-I/en
>> [3]: https://www.itu.int/rec/R-REC-BT.709-6-201506-I/en
>> [4]: https://www.itu.int/rec/R-REC-BT.2020-2-201510-I/en
>> [5]: https://lists.freedesktop.org/archives/igt-dev/2024-January/066937.html
>> [6]: https://lore.kernel.org/dri-devel/20230414135151.75975-2-mcanal@igalia.com/
>>
>> Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
>> ---
>> Changes in v2:
>> - Use EXPORT_SYMBOL_IF_KUNIT instead of including the .c test
>>   file (Maxime)
>> - Link to v1: https://lore.kernel.org/r/20240105-vkms-yuv-v1-0-34c4cd3455e0@riseup.net
>>
>> ---
>> Arthur Grillo (7):
>>       drm/vkms: Use drm_frame directly
>>       drm/vkms: Add support for multy-planar framebuffers
>>       drm/vkms: Add range and encoding properties to pixel_read function
>>       drm/vkms: Add chroma subsampling
>>       drm/vkms: Add YUV support
>>       drm/vkms: Drop YUV formats TODO
>>       drm/vkms: Create KUnit tests for YUV conversions
>>
>>  Documentation/gpu/vkms.rst                    |   3 +-
>>  drivers/gpu/drm/vkms/Kconfig                  |  15 ++
>>  drivers/gpu/drm/vkms/Makefile                 |   1 +
>>  drivers/gpu/drm/vkms/tests/.kunitconfig       |   4 +
>>  drivers/gpu/drm/vkms/tests/Makefile           |   3 +
>>  drivers/gpu/drm/vkms/tests/vkms_format_test.c | 156 ++++++++++++++++
>>  drivers/gpu/drm/vkms/vkms_drv.h               |   6 +-
>>  drivers/gpu/drm/vkms/vkms_formats.c           | 247 ++++++++++++++++++++++----
>>  drivers/gpu/drm/vkms/vkms_formats.h           |   9 +
>>  drivers/gpu/drm/vkms/vkms_plane.c             |  26 ++-
>>  drivers/gpu/drm/vkms/vkms_writeback.c         |   5 -
>>  11 files changed, 426 insertions(+), 49 deletions(-)
>> ---
>> base-commit: eeb8e8d9f124f279e80ae679f4ba6e822ce4f95f
>> change-id: 20231226-vkms-yuv-6f7859f32df8
>>
>> Best regards,
>> -- 
>> Arthur Grillo <arthurgrillo@riseup.net>
>>
>