linux-kernel - Re: [PATCH v2 0/7] Add YUV formats to VKMS

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Date: Thu, 29 Feb 2024 18:52:11 +0100
From: Sebastian Wick <sebastian.wick@...hat.com>
To: Arthur Grillo <arthurgrillo@...eup.net>
Cc: Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>,
	Haneen Mohammed <hamohammed.sa@...il.com>,
	Harry Wentland <harry.wentland@....com>,
	Jonathan Corbet <corbet@....net>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Maíra Canal <mairacanal@...eup.net>,
	Melissa Wen <melissa.srw@...il.com>,
	Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 0/7] Add YUV formats to VKMS

On Wed, Feb 28, 2024 at 08:42:41PM -0300, Arthur Grillo wrote:
> 
> 
> 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.

I'm glad this is useful for you! We also used it for our color-and-hdr
project https://gitlab.freedesktop.org/pq/color-and-hdr/.

> [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@...el_format
> >> - kms_plane@...el_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@...eup.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@...eup.net>
> >>
> > 
>