Message-ID: <Zzt1o-Cwe1fRLRW6@louis-chauvet-laptop>
Date: Mon, 18 Nov 2024 18:13:07 +0100
From: Louis Chauvet <louis.chauvet@...tlin.com>
To: José Expósito <jose.exposito89@...il.com>
Cc: airlied@...il.com, arthurgrillo@...eup.net, corbet@....net,
	dri-devel@...ts.freedesktop.org, hamohammed.sa@...il.com,
	helen.koike@...labora.com, jeremie.dautheribes@...tlin.com,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	maarten.lankhorst@...ux.intel.com, mairacanal@...eup.net,
	marcheu@...gle.com, mcanal@...lia.com, melissa.srw@...il.com,
	miquel.raynal@...tlin.com, mripard@...nel.org,
	nicolejadeyee@...gle.com, pekka.paalanen@...labora.com,
	pekka.paalanen@...oniitty.fi, rdunlap@...radead.org,
	rodrigosiqueiramelo@...il.com, seanpaul@...gle.com,
	simona.vetter@...ll.ch, simona@...ll.ch,
	thomas.petazzoni@...tlin.com, tzimmermann@...e.de
Subject: Re: [PATCH v13 0/9] drm/vkms: Reimplement line-per-line pixel
 conversion for plane reading

On 18/11/24 - 18:10, José Expósito wrote:
> Hi Louis,
> 
> > 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 multiple parts:
> > - PATCH 1 to 3: no functional change is intended, only some formatting and
> >   documenting (PATCH 2 is taken from [2])
> > - PATCH 4 to 7: Some preparation work not directly related to the
> >   line-by-line algorithm
> > - PATCH 8: main patch for this series, it reintroduce the
> >   line-by-line algorithm
> > - PATCH 9: Remove useless drm_simplify_rotation
> > - Rest of the series: moved to a new series to merge this one, see the new 
> >   series "Add YUV ad R1..8 formats support to VKMS"
> > 
> > The PATCH 8 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).
> > 
> > I did not changed any expected test results as VKMS seems to have some 
> > existing issue:
> > https://gitlab.freedesktop.org/jim.cromie/kernel-drm-next-dd/-/jobs/61484201
> > https://gitlab.freedesktop.org/jim.cromie/kernel-drm-next-dd/-/jobs/61803193
> > https://gitlab.freedesktop.org/louischauvet/kernel/-/jobs/65944002
> > 
> > To properly test the rotation algorithm, I had to implement a new IGT
> > test [8]. This helped to found one issue in the YUV rotation algortihm.
> > 
> > My series was mainly tested with:
> > - kms_plane (for color conversions)
> > - kms_rotation_crc (for a subset of rotation and formats)
> > - kms_rotation (to test all rotation and formats combinations) [8]
> > - kms_cursor_crc (for translations)
> > The benchmark used to measure the improvment was done with
> > kms_fb_stress [10] with some modifications:
> > - Fixing the writeback format to XRGB8888
> > - Using a primary plane with odd dimension to avoid failures due to YUV
> >   alignment
> > The KMS structure was:
> > 	CRTC:
> > 		rectangle: 4096x2160+0+0
> > 	primary:
> > 		format: ABGR16161616
> > 		rectangle: 3640x2160+101+0
> > 	writeback:
> > 		format: XRGB8888
> > 		rectangle: 4096x2160+0+0
> > Results (on my computer):
> > 
> > 8356b9790650: drm/test: Add test cases for drm_rect_rotate_inv() (before any regression)
> > 322d716a3e8a: drm/vkms: isolate pixel conversion functionality (first regression)
> > cc4fd2934d41: drm/vkms: Isolate writeback pixel conversion functions (second regression)
> > 2c3d1bd284c5: drm/panel: simple: Add Microtips Technology MF-103HIEB0GA0 panel (current drm-misc-next)
> > 
> >  Used format  | This series | 2c3d1bd284c5 | cc4fd2934d41 | 322d716a3e8a | 8356b9790650 |
> > --------------+-------------+--------------+--------------+--------------+--------------+
> >  XRGB8888     |  13.261666s |   14.289582s |   10.731272s |    9.480001s |    9.277507s |
> >  XRGB16161616 |  13.282479s |   13.918926s |   10.712616s |    9.776903s |    9.291766s |
> >  RGB565       | 136.154163s |  141.646489s |  101.744050s |  103.712164s |   87.860923s |
> > 
> > This is a 5-10% improvment of the performance. More work need to be done
> > on the writeback to gain more.
> > 
> > [1]: https://lore.kernel.org/all/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/
> > [8]: https://lore.kernel.org/r/20240313-new_rotation-v2-0-6230fd5cae59@bootlin.com
> > [9]: https://lore.kernel.org/dri-devel/20240306-louis-vkms-conv-v1-1-5bfe7d129fdd@riseup.net/
> > [10]: https://lore.kernel.org/all/20240422-kms_fb_stress-dev-v5-0-0c577163dc88@riseup.net/
> > 
> > To: Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>
> > To: Melissa Wen <melissa.srw@...il.com>
> > To: Maíra Canal <mairacanal@...eup.net>
> > To: Haneen Mohammed <hamohammed.sa@...il.com>
> > To: Daniel Vetter <daniel@...ll.ch>
> > To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
> > To: Maxime Ripard <mripard@...nel.org>
> > To: Thomas Zimmermann <tzimmermann@...e.de>
> > To: David Airlie <airlied@...il.com>
> > To: rdunlap@...radead.org
> > To: arthurgrillo@...eup.net
> > To: Jonathan Corbet <corbet@....net>
> > To: pekka.paalanen@...oniitty.fi
> > Cc: dri-devel@...ts.freedesktop.org
> > Cc: linux-kernel@...r.kernel.org
> > Cc: jeremie.dautheribes@...tlin.com
> > Cc: miquel.raynal@...tlin.com
> > Cc: thomas.petazzoni@...tlin.com
> > Cc: seanpaul@...gle.com
> > Cc: marcheu@...gle.com
> > Cc: nicolejadeyee@...gle.com
> > Signed-off-by: Louis Chauvet <louis.chauvet@...tlin.com>
> 
> Thanks for working on this. I reviewed the series and, with the exception of
> a couple of *very* minor comments, it looks good to me.

I already have to send a v14 so don't worry, I sent the v13 before 
commiting on vkms...

> Feel free to add to the entire series:
> Reviewed-by: José Expósito <jose.exposito89@...il.com>

Thanks a lot! I will add it.
 
> > Changes in v13:
> > - Removed the YUV part to prepare the merge
> > - Add Acked-by from Maíra
> > - Link to v12: https://lore.kernel.org/r/20241007-yuv-v12-0-01c1ada6fec8@bootlin.com
> > Changes in v12:
> > - Fix documentation issues as suggested by Randy
> > - Link to v11: https://lore.kernel.org/r/20240930-yuv-v11-0-4b1a26bcfc96@bootlin.com
> > Changes in v11:
> > - Remove documentation patch (already merged)
> > - Fix sparse warning about documentation
> > - Link to v10: https://lore.kernel.org/r/20240809-yuv-v10-0-1a7c764166f7@bootlin.com
> > Changes in v10:
> > - Properly remove the patch introducing dummy read/write functions
> > - PATCH 8/16: Format fixups
> > - PATCH 9/16: Format fixups
> > - PATCH 11/16: Format fixups
> > - PATCH 14/16: Fix test compilation, add module description
> > - Link to v9: https://lore.kernel.org/r/20240802-yuv-v9-0-08a706669e16@bootlin.com
> > Changes in v9:
> > - PATCH 3/17: Fix docs as Maíra suggested
> > - PATCH 4,6,10,12,15,17/17: Fix sparse warning about __le16 casting
> > - Link to v8: https://lore.kernel.org/all/20240516-yuv-v8-0-cf8d6f86430e@bootlin.com/
> > Changes in v8:
> > - PATCH 7/17: Update pitch access to use the proper value for block
> >   formats
> > - PATCH 9/17: Update pitch access to use the proper value for block
> >   formats
> > - Link to v7: https://lore.kernel.org/r/20240513-yuv-v7-0-380e9ffec502@bootlin.com
> > Changes in v7:
> > - Some typos and indent fixes
> > - Add Review-By, Acked-By
> > - PATCH 3/17: Clarify src/dst unit
> > - PATCH 9/17: Clarify documentation
> > - PATCH 9/17: Restrict conditions for direction
> > - PATCH 9/17: Rename get_block_step_byte to get_block_step_bytes
> > - PATCH 10/17: Clarify kernel doc for clamp_line_coordinates, blend_line,
> >   pixel_read_line_t
> > - PATCH 10/17: Fix the case when src_*_start >= fb->width/height
> > - PATCH 10/17: Change y in blend to be an int
> > - PATCH 10/17: Clarify documentation for read functions
> > - PATCH 12/17: Fix the type of rgb variables in argb_u16_from_yuv888
> > - PATCH 12/17: Move comments at the right place, remove useless ones
> > - PATCH 12/17: Add missing const
> > - PATCH 17/17: Use drm_format_info_bpp and computation to avoid hard-coded
> >   values
> > - Link to v6: https://lore.kernel.org/r/20240409-yuv-v6-0-de1c5728fd70@bootlin.com
> > Changes in v6:
> > - Add Randy
> > - Add Review-By and Acked-By
> > - PATCH 2/17: Remove useless newline
> > - PATCH 3/17: Fix kernel doc
> > - PATCH 4/17: Fix typo in git commit
> > - PATCH 4/17: Fix kernel doc and simplify brief description of typedef
> > - PATCH 5/17: Change black default color to Magenta
> > - PATCH 5/17: Fix wording in comment
> > - PATCH 7/17: Fix typo in packed_pixel_offset
> > - PATCH 7/17: Add WARN_ON for currently not supported formats
> > - PATCH 8/17: Rename x_limit to pixel_count
> > - PATCH 8/17: Clarify kernel doc for pre_mul_alpha_blend
> > - PATCH 9/17: Rename get_step_next_block to get_block_step_bytes
> > - PATCH 9/17: Change kernel doc order
> > - PATCH 9/17: Rework the direction_for_rotation function to use drm
> >   helpers
> > - PATCH 9/17: Add a warn in direction_for_rotation if the result is not
> >   expected
> > - PATCH 10/17: Reword the comment of pixel color conversion functions
> > - PATCH 10/17: Refactor the blending function to extract functions
> > - PATCH 11/17: Remove useless drm_rotation_simplify
> > - PATCH 12/17: Fix typo in comments
> > - PATCH 12/17: Remove useless define
> > - PATCH 12/17: Fix some comments typo and kernel doc
> > - PATCH 12/17: Add a comma at the end of the vkms_formats list
> > - PATCH 12/17: Use copy of matrix instead of pointers
> > - PATCH 12/17: Use 16 bit range for yuv conversion
> > - PATCH 17/17: Add a comma at the end of the vkms_formats list
> > - PATCH 17/17: Add assertions
> > - PATCH 17/17: Fix color conversion... Next time I will read the doc
> >   twice...
> > - Link to v5: https://lore.kernel.org/r/20240313-yuv-v5-0-e610cbd03f52@bootlin.com
> > Changes in v5:
> > - All patches: fix some formatting issues
> > - PATCH 4/16: Use the correct formatter for 4cc code
> > - PATCH 7/16: Update the pixel accessors to also return the pixel position
> >   inside a block.
> > - PATCH 8/16: Fix a temporary bug
> > - PATCH 9/16: Update the get_step_1x1 to get_step_next_block and update
> >   the documentation
> > - PATCH 10/16: Update to uses the new pixel accessors
> > - PATCH 10/16: Reword some comments
> > - PATCH 11/16: Update to use the new pixel accessors
> > - PATCH 11/16: Fix a bug in the subsampling offset for inverted reading
> >   (right to left/bottom to top). Found by [8].
> > - PATCH 11/16: Apply Arthur's modifications (comments, algorithm
> >   clarification)
> > - PATCH 11/16: Use the correct formatter for 4cc code
> > - PATCH 11/16: Update to use the new get_step_next_block
> > - PATCH 14/16: Apply Arthur's modification (comments, compilation issue)
> > - PATCH 15/16: Add Arthur's patch to explain the kunit tests
> > - PATCH 16/16: Introduce DRM_FORMAT_R* support.
> > - Link to v4: https://lore.kernel.org/r/20240304-yuv-v4-0-76beac8e9793@bootlin.com
> > Changes in v4:
> > - PATCH 3/14: Update comments for get_pixel_* functions
> > - PATCH 4/14: Add WARN when trying to get unsupported pixel_* functions
> > - PATCH 5/14: Create dummy pixel reader/writer to avoid NULL
> >   function pointers and kernel OOPS
> > - PATCH 6/14: Added the usage of const pointers when needed
> > - PATCH 7/14: Extraction of pixel accessors modification
> > - PATCH 8/14: Extraction of the blending function modification
> > - PATCH 9/14: Extraction of the pixel_read_direction enum
> > - PATCH 10/14: Update direction_for_rotation documentation
> > - PATCH 10/14: Rename conversion functions to be explicit
> > - PATCH 10/14: Replace while(count) by while(out_pixel<end) in read_line
> >   callbacks. It avoid a new variable+addition in the composition hot path.
> > - PATCH 11/14: Rename conversion functions to be explicit
> > - PATCH 11/14: Update the documentation for get_subsampling_offset
> > - PATCH 11/14: Add the matrix_conversion structure to remove a test from
> >   the hot path.
> > - PATCH 11/14: Upadate matrix values to use 32.32 fixed floats for
> >   conversion
> > - PATCH 12/14: Update commit message
> > - PATCH 14/14: Change kunit expected value
> > - Link to v3: https://lore.kernel.org/r/20240226-yuv-v3-0-ff662f0994db@bootlin.com
> > Changes in v3:
> > - Correction of remaining git-rebase artefacts
> > - Added Pekka in copy of this patch
> > - Link to v2: https://lore.kernel.org/r/20240223-yuv-v2-0-aa6be2827bb7@bootlin.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 (1):
> >       drm/vkms: Use drm_frame directly
> > 
> > Louis Chauvet (8):
> >       drm/vkms: Code formatting
> >       drm/vkms: Add typedef and documentation for pixel_read and pixel_write functions
> >       drm/vkms: Use const for input pointers in pixel_read an pixel_write functions
> >       drm/vkms: Update pixels accessor to support packed and multi-plane formats.
> >       drm/vkms: Avoid computing blending limits inside pre_mul_alpha_blend
> >       drm/vkms: Introduce pixel_read_direction enum
> >       drm/vkms: Re-introduce line-per-line composition algorithm
> >       drm/vkms: Remove useless drm_rotation_simplify
> > 
> >  drivers/gpu/drm/vkms/vkms_composer.c  | 312 ++++++++++++++++++++------
> >  drivers/gpu/drm/vkms/vkms_crtc.c      |   6 +-
> >  drivers/gpu/drm/vkms/vkms_drv.c       |   3 +-
> >  drivers/gpu/drm/vkms/vkms_drv.h       |  55 ++++-
> >  drivers/gpu/drm/vkms/vkms_formats.c   | 409 ++++++++++++++++++++++++----------
> >  drivers/gpu/drm/vkms/vkms_formats.h   |   4 +-
> >  drivers/gpu/drm/vkms/vkms_plane.c     |  17 +-
> >  drivers/gpu/drm/vkms/vkms_writeback.c |   5 -
> >  8 files changed, 588 insertions(+), 223 deletions(-)
> > ---
> > base-commit: 623b1e4d2eace0958996995f9f88cb659a6f69dd
> > change-id: 20240201-yuv-1337d90d9576
> > 
> > Best regards,
> > 

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