[PATCH v2 0/9] drm/vkms: Reimplement line-per-line pixel conversion for plane reading

[Louis Chauvet]

This patchset is the second version of [1]. It is almost a complete 
rewrite to use a line-by-line algorithm for the composition.
It can be divided in three parts:
- PATCH 1 to 4: no functional change is intended, only some formatting and 
documenting
(PATCH 2 is taken from [2])
- PATCH 5: main patch for this series, it reintroduce the 
line-by-line algorithm
- PATCH 6 to 9: taken from Arthur's series [2], with sometimes adaptation 
to use the pixel-by-pixel algorithm.

The PATCH 5 aims to restore the line-by-line pixel reading algorithm. It 
was introduced in 8ba1648567e2 ("drm: vkms: Refactor the plane composer to 
accept new formats") but removed in 8ba1648567e2 ("drm: vkms: Refactor the 
plane composer to accept new formats") in a over-simplification effort. 
At this time, nobody noticed the performance impact of this commit. After 
the first iteration of my series, poeple notice performance impact, and it 
was the case. Pekka suggested to reimplement the line-by-line algorithm.

Expiriments on my side shown great improvement for the line-by-line 
algorithm, and the performances are the same as the original line-by-line 
algorithm. I targeted my effort to make the code working for all the 
rotations and translations. The usage of helpers from drm_rect_* avoid 
reimplementing existing logic.

The only "complex" part remaining is the clipping of the coordinate to 
avoid reading/writing outside of src/dst. Thus I added a lot of comments 
to help when someone will want to add some features (framebuffer resizing 
for example).

The YUV part is not mandatory for this series, but as my first effort was 
to help the integration of YUV, I decided to rebase Arthur's series on 
mine to help. I took [3], [4], [5] and [6] and adapted them to use the 
line-by-line reading. If I did something wrong here, please let me 
know.

My series was mainly tested with:
- kms_plane (for color conversions)
- kms_rotation_crc (for rotations of planes)
- kms_cursor_crc (for translations)
The benchmark used to measure the improvment was done with:
- kms_fb_stress

[1]: https://lore.kernel.org/r/20240201-yuv-v1-0-3ca376f27632@bootlin.com
[2]: https://lore.kernel.org/all/20240110-vkms-yuv-v2-0-952fcaa5a193@riseup.net/
[3]: https://lore.kernel.org/all/20240110-vkms-yuv-v2-3-952fcaa5a193@riseup.net/
[4]: https://lore.kernel.org/all/20240110-vkms-yuv-v2-5-952fcaa5a193@riseup.net/
[5]: https://lore.kernel.org/all/20240110-vkms-yuv-v2-6-952fcaa5a193@riseup.net/
[6]: https://lore.kernel.org/all/20240110-vkms-yuv-v2-7-952fcaa5a193@riseup.net/

To: Rodrigo Siqueira <rodrigosiqueiramelo at gmail.com>
To: Melissa Wen <melissa.srw at gmail.com>
To: Maíra Canal <mairacanal at riseup.net>
To: Haneen Mohammed <hamohammed.sa at gmail.com>
To: Daniel Vetter <daniel at ffwll.ch>
To: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
To: Maxime Ripard <mripard at kernel.org>
To: Thomas Zimmermann <tzimmermann at suse.de>
To: David Airlie <airlied at gmail.com>
To: arthurgrillo at riseup.net
To: Jonathan Corbet <corbet at lwn.net>
Cc: dri-devel at lists.freedesktop.org
Cc: linux-kernel at vger.kernel.org
Cc: jeremie.dautheribes at bootlin.com
Cc: miquel.raynal at bootlin.com
Cc: thomas.petazzoni at bootlin.com
Signed-off-by: Louis Chauvet <louis.chauvet at bootlin.com>

Note: after my changes, those tests seems to pass, so [7] may need 
updating (I did not check, it was maybe already the case):
- kms_cursor_legacy at flip-vs-cursor-atomic
- kms_pipe_crc_basic at nonblocking-crc
- kms_pipe_crc_basic at nonblocking-crc-frame-sequence
- kms_writeback at writeback-pixel-formats
- kms_writeback at writeback-invalid-parameters
- kms_flip at flip-vs-absolute-wf_vblank-interruptible
And those tests pass, I did not investigate why the runners fails:
- kms_flip at flip-vs-expired-vblank-interruptible
- kms_flip at flip-vs-expired-vblank
- kms_flip at plain-flip-fb-recreate
- kms_flip at plain-flip-fb-recreate-interruptible
- kms_flip at plain-flip-ts-check-interruptible
- kms_cursor_legacy at cursorA-vs-flipA-toggle
- kms_pipe_crc_basic at nonblocking-crc
- kms_prop_blob at invalid-get-prop
- kms_flip at flip-vs-absolute-wf_vblank-interruptible
- kms_invalid_mode at zero-hdisplay
- kms_invalid_mode at bad-vtotal
- kms_cursor_crc.* (everything is SUCCEED or SKIP, but no fails)

[7]: https://lore.kernel.org/all/20240201065346.801038-1-vignesh.raman@collabora.com/

Changes in v2:
- Rebased the series on top of drm-misc/drm-misc-net
- Extract the typedef for pixel_read/pixel_write
- Introduce the line-by-line algorithm per pixel format
- Add some documentation for existing and new code
- Port the series [1] to use line-by-line algorithm
- Link to v1: https://lore.kernel.org/r/20240201-yuv-v1-0-3ca376f27632@bootlin.com

---
Arthur Grillo (5):
      drm/vkms: Use drm_frame directly
      drm/vkms: Add YUV support
      drm/vkms: Add range and encoding properties to pixel_read function
      drm/vkms: Drop YUV formats TODO
      drm/vkms: Create KUnit tests for YUV conversions

Louis Chauvet (4):
      drm/vkms: Code formatting
      drm/vkms: write/update the documentation for pixel conversion and pixel write functions
      drm/vkms: Add typedef and documentation for pixel_read and pixel_write functions
      drm/vkms: Re-introduce line-per-line composition algorithm

 Documentation/gpu/vkms.rst                    |   3 +-
 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 | 155 +++++++
 drivers/gpu/drm/vkms/vkms_composer.c          | 233 ++++++++---
 drivers/gpu/drm/vkms/vkms_crtc.c              |   6 +-
 drivers/gpu/drm/vkms/vkms_drv.c               |   3 +-
 drivers/gpu/drm/vkms/vkms_drv.h               |  56 ++-
 drivers/gpu/drm/vkms/vkms_formats.c           | 565 +++++++++++++++++++++-----
 drivers/gpu/drm/vkms/vkms_formats.h           |  13 +-
 drivers/gpu/drm/vkms/vkms_plane.c             |  50 ++-
 drivers/gpu/drm/vkms/vkms_writeback.c         |  14 +-
 13 files changed, 916 insertions(+), 190 deletions(-)
---
base-commit: aa1267e673fe5307cf00d02add4017d2878598b6
change-id: 20240201-yuv-1337d90d9576

Best regards,
-- 
Louis Chauvet <louis.chauvet at bootlin.com>