Re: [PATCH v11 00/56] Add DELETE_BUF ioctl

[Hans Verkuil]

Hi Benjamin,

On 12/10/2023 13:45, Benjamin Gaignard wrote:
> Unlike when resolution change on keyframes, dynamic resolution change
> on inter frames doesn't allow to do a stream off/on sequence because
> it is need to keep all previous references alive to decode inter frames.
> This constraint have two main problems:
> - more memory consumption.
> - more buffers in use.
> To solve these issue this series introduce DELETE_BUFS ioctl and remove
> the 32 buffers limit per queue.
> 
> VP9 conformance tests using fluster give a score of 210/305.
> The 20 resize inter tests (vp90-2-21-resize_inter_* files) are ok
> but require to use postprocessor.
> 
> Kernel branch is available here:
> https://gitlab.collabora.com/benjamin.gaignard/for-upstream/-/commits/remove_vb2_queue_limit_v11
> 
> GStreamer branch to use DELETE_BUF ioctl and testing dynamic resolution
> change is here:
> https://gitlab.freedesktop.org/benjamin.gaignard1/gstreamer/-/commits/VP9_drc

I did another review. Mainly small stuff, but I realized in my review of 40/56 that
the use of min_buffers_needed is a mess, and you will need to revisit any driver
patches where you change that value, or where you drop the number of buffers check
in queue_setup because you rely on min_buffers_needed.

I think it is likely that we need to take another very good look at this before we
implement VIDIOC_DELETE_BUFS.

I have also posted a PR where I ask Mauro to merge patch 07/56 for 6.7 to get
the vb2_get_num_buffers helper in. We'll see if that will happen since it is a
bit late for that.

Regards,

	Hans

> 
> changes in version 11:
> - Patches ordering:
>   1 to 3: clean up
>   3 to 42: use vb2_get_buffer() and vb2_get_num_buffers()
>   43 to 46: allow to use more than 32 buffers per queue
>   47 to 50: allow verisilicon driver to do VP9 dynamic resolution change
>             (which was the main purpose of this work)
>   51 to 56: prepare and introduce delete buffers feature.
> - Add a patch to rename 'off' to offset.
> - Add maintainers CC to drivers patches
> 
> changes in version 10:
> - Make BUFFER_INDEX_MASK definition more readable
> - Rebase on media_stage/master branch and add a patch for nuvoton
>   driver.
> - Fix issue on patch 13
> 
> changes in version 9:
> - BUFFER_INDEX_MASK now depends on PAGE_SHIFT value to match
>   architectures requirements.
> - Correctly initialize max_num_buffers in vb2_core_queue_init()
> - run 'test-media -kmemleak mc' on top of the series and on patches 1 to 47 without failures.
> - fix compilation issue in patch 50
> 
> changes in version 8:
> - Add V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS and new 'max_buffers' field in v4l2_create_buffers
>   structure to report the maximum number of buffers that a queue could allocate.
> - Add V4L2_BUF_CAP_SUPPORTS_DELETE_BUFS to indicate that a queue support
>   DELETE_BUFS ioctl.
> - Make some test drivers use more than 32 buffers and DELETE_BUFS ioctl.
> - Fix remarks done by Hans
> - Move "media: core: Rework how create_buf index returned value is
>   computed" patch to the top of the serie.
> 
> changes in version 7:
> - Use a bitmap to know which entries are valid in queue bufs array.
>   The number of buffers in the queue could must calculated from the
>   bitmap so num_buffers becomes useless. This led to add quite few
>   patches to remove it from all the drivers.
>   Note: despiste my attention I may have miss some calls to
>   num_buffers...
> - Split patches to make them more readable.
> - Run v4l2-compliance with additional delete-bufs tests.
> - Run ./test-media -kmemleak vivid and no more failures.
>   Note: I had to remove USERPTR streaming test because they to much
>   frequentely hit get_framevec bug. It is not related to my series
>   since this happens all the time on master branch.
> - Fix Hans remarks on v6
> 
> changes in version 6:
> - Get a patch per driver to use vb2_get_buffer() instead of directly access
>   to queue buffers array.
> - Add lock in vb2_core_delete_buf()
> - Use vb2_buffer instead of index
> - Fix various comments
> - Change buffer index name to BUFFER_INDEX_MASK
> - Stop spamming kernel log with unbalanced counters
> 
> Benjamin Gaignard (56):
>   media: videobuf2: Rename offset parameter
>   media: videobuf2: Rework offset 'cookie' encoding pattern
>   media: videobuf2: Stop spamming kernel log with all queue counter
>   media: videobuf2: Use vb2_buffer instead of index
>   media: videobuf2: Access vb2_queue bufs array through helper functions
>   media: videobuf2: Remove duplicated index vs q->num_buffers check
>   media: videobuf2: Add helper to get queue number of buffers
>   media: videobuf2: Use vb2_get_num_buffers() helper
>   media: amphion: Use vb2_get_buffer() instead of directly access to
>     buffers array
>   media: amphion: Stop direct calls to queue num_buffers field
>   media: mediatek: jpeg: Use vb2_get_buffer() instead of directly access
>     to buffers array
>   media: mediatek: vdec: Remove useless loop
>   media: mediatek: vcodec: Stop direct calls to queue num_buffers field
>   media: sti: hva: Use vb2_get_buffer() instead of directly access to
>     buffers array
>   media: visl: Use vb2_get_buffer() instead of directly access to
>     buffers array
>   media: atomisp: Use vb2_get_buffer() instead of directly access to
>     buffers array
>   media: atomisp: Stop direct calls to queue num_buffers field
>   media: dvb-core: Use vb2_get_buffer() instead of directly access to
>     buffers array
>   media: dvb-core: Do not initialize twice queue num_buffer field
>   media: dvb-frontends: rtl2832_srd: Use queue min_buffers_needed field
>   media: video-i2c: Set min_buffers_needed to 2
>   media: pci: cx18: Set correct value to min_buffers_needed field
>   media: pci: dt3155: Remove useless check
>   media: pci: netup_unidvb: Remove useless number of buffers check
>   media: pci: tw68: Stop direct calls to queue num_buffers field
>   media: pci: tw686x: Set min_buffers_needed to 3
>   media: coda: Stop direct calls to queue num_buffers field
>   media: nxp: Stop direct calls to queue num_buffers field
>   media: renesas: Set min_buffers_needed to 16
>   media: ti: Use queue min_buffers_needed field to set the min number of
>     buffers
>   media: verisilicon: Stop direct calls to queue num_buffers field
>   media: test-drivers: Stop direct calls to queue num_buffers field
>   media: usb: airspy: Set min_buffers_needed to 8
>   media: usb: cx231xx: Set min_buffers_needed to CX231XX_MIN_BUF
>   media: usb: hackrf: Set min_buffers_needed to 8
>   media: usb: usbtv: Set min_buffers_needed to 2
>   media: imx: Stop direct calls to queue num_buffers field
>   media: meson: vdec: Stop direct calls to queue num_buffers field
>   touchscreen: sur40: Stop direct calls to queue num_buffers field
>   sample: v4l: Stop direct calls to queue num_buffers field
>   media: cedrus: Stop direct calls to queue num_buffers field
>   media: nuvoton: Stop direct calls to queue num_buffers field
>   media: videobuf2: Be more flexible on the number of queue stored
>     buffers
>   media: core: Report the maximum possible number of buffers for the
>     queue
>   media: test-drivers: vivid: Increase max supported buffers for capture
>     queues
>   media: test-drivers: vicodec: Increase max supported capture queue
>     buffers
>   media: verisilicon: Refactor postprocessor to store more buffers
>   media: verisilicon: Store chroma and motion vectors offset
>   media: verisilicon: g2: Use common helpers to compute chroma and mv
>     offsets
>   media: verisilicon: vp9: Allow to change resolution while streaming
>   media: core: Rework how create_buf index returned value is computed
>   media: core: Add bitmap manage bufs array entries
>   media: core: Free range of buffers
>   media: v4l2: Add DELETE_BUFS ioctl
>   media: v4l2: Add mem2mem helpers for DELETE_BUFS ioctl
>   media: test-drivers: Use helper for DELETE_BUFS ioctl
> 
>  .../userspace-api/media/v4l/user-func.rst     |   1 +
>  .../media/v4l/vidioc-create-bufs.rst          |   8 +-
>  .../media/v4l/vidioc-delete-bufs.rst          |  80 +++
>  .../media/v4l/vidioc-reqbufs.rst              |   2 +
>  drivers/input/touchscreen/sur40.c             |   5 +-
>  .../media/common/videobuf2/videobuf2-core.c   | 567 +++++++++++-------
>  .../media/common/videobuf2/videobuf2-v4l2.c   | 116 +++-
>  drivers/media/dvb-core/dvb_vb2.c              |  17 +-
>  drivers/media/dvb-frontends/rtl2832_sdr.c     |   9 +-
>  drivers/media/i2c/video-i2c.c                 |   5 +-
>  drivers/media/pci/cx18/cx18-streams.c         |  13 +-
>  drivers/media/pci/dt3155/dt3155.c             |   2 -
>  .../pci/netup_unidvb/netup_unidvb_core.c      |   4 +-
>  drivers/media/pci/tw68/tw68-video.c           |   6 +-
>  drivers/media/pci/tw686x/tw686x-video.c       |  13 +-
>  drivers/media/platform/amphion/vpu_dbg.c      |  30 +-
>  drivers/media/platform/amphion/vpu_v4l2.c     |   4 +-
>  .../media/platform/chips-media/coda-common.c  |   2 +-
>  .../platform/mediatek/jpeg/mtk_jpeg_core.c    |   7 +-
>  .../vcodec/decoder/vdec/vdec_vp9_req_lat_if.c |   9 +-
>  .../mediatek/vcodec/encoder/mtk_vcodec_enc.c  |   2 +-
>  drivers/media/platform/nuvoton/npcm-video.c   |   2 +-
>  drivers/media/platform/nxp/imx7-media-csi.c   |   7 +-
>  drivers/media/platform/renesas/rcar_drif.c    |   8 +-
>  drivers/media/platform/st/sti/hva/hva-v4l2.c  |   9 +-
>  .../media/platform/ti/am437x/am437x-vpfe.c    |   7 +-
>  drivers/media/platform/ti/cal/cal-video.c     |   5 +-
>  .../media/platform/ti/davinci/vpif_capture.c  |   5 +-
>  .../media/platform/ti/davinci/vpif_display.c  |   5 +-
>  drivers/media/platform/ti/omap/omap_vout.c    |   5 +-
>  drivers/media/platform/verisilicon/hantro.h   |   9 +-
>  .../media/platform/verisilicon/hantro_drv.c   |   5 +-
>  .../media/platform/verisilicon/hantro_g2.c    |  14 +
>  .../platform/verisilicon/hantro_g2_hevc_dec.c |  18 +-
>  .../platform/verisilicon/hantro_g2_vp9_dec.c  |  28 +-
>  .../media/platform/verisilicon/hantro_hw.h    |   7 +-
>  .../platform/verisilicon/hantro_postproc.c    |  93 ++-
>  .../media/platform/verisilicon/hantro_v4l2.c  |  27 +-
>  .../media/test-drivers/vicodec/vicodec-core.c |   3 +
>  drivers/media/test-drivers/vim2m.c            |   2 +
>  .../media/test-drivers/vimc/vimc-capture.c    |   2 +
>  drivers/media/test-drivers/visl/visl-dec.c    |  32 +-
>  drivers/media/test-drivers/visl/visl-video.c  |   2 +
>  drivers/media/test-drivers/vivid/vivid-core.c |  14 +
>  .../media/test-drivers/vivid/vivid-meta-cap.c |   3 -
>  .../media/test-drivers/vivid/vivid-meta-out.c |   5 +-
>  .../test-drivers/vivid/vivid-touch-cap.c      |   5 +-
>  .../media/test-drivers/vivid/vivid-vbi-cap.c  |   5 +-
>  .../media/test-drivers/vivid/vivid-vbi-out.c  |   5 +-
>  .../media/test-drivers/vivid/vivid-vid-cap.c  |   5 +-
>  .../media/test-drivers/vivid/vivid-vid-out.c  |   5 +-
>  drivers/media/usb/airspy/airspy.c             |   9 +-
>  drivers/media/usb/cx231xx/cx231xx-417.c       |   4 +-
>  drivers/media/usb/cx231xx/cx231xx-video.c     |   4 +-
>  drivers/media/usb/hackrf/hackrf.c             |   9 +-
>  drivers/media/usb/usbtv/usbtv-video.c         |   3 +-
>  drivers/media/v4l2-core/v4l2-dev.c            |   1 +
>  drivers/media/v4l2-core/v4l2-ioctl.c          |  21 +-
>  drivers/media/v4l2-core/v4l2-mem2mem.c        |  20 +
>  .../staging/media/atomisp/pci/atomisp_ioctl.c |   4 +-
>  drivers/staging/media/imx/imx-media-capture.c |   7 +-
>  drivers/staging/media/meson/vdec/vdec.c       |  13 +-
>  .../staging/media/sunxi/cedrus/cedrus_h264.c  |   8 +-
>  .../staging/media/sunxi/cedrus/cedrus_h265.c  |   9 +-
>  include/media/v4l2-ioctl.h                    |   4 +
>  include/media/v4l2-mem2mem.h                  |  12 +
>  include/media/videobuf2-core.h                |  65 +-
>  include/media/videobuf2-v4l2.h                |  13 +
>  include/uapi/linux/videodev2.h                |  24 +-
>  samples/v4l/v4l2-pci-skeleton.c               |   5 +-
>  70 files changed, 972 insertions(+), 507 deletions(-)
>  create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst
>