From: Hans Verkuil <hansverk@xxxxxxxxx> As was discussed here (among other places): https://lkml.org/lkml/2018/10/19/440 using capture queue buffer indices to refer to reference frames is not a good idea. A better idea is to use a 'tag' where the application can assign a u64 tag to an output buffer, which is then copied to the capture buffer(s) derived from the output buffer. A u64 is chosen since this allows userspace to also use pointers to internal structures as 'tag'. The first three patches add core tag support, the next patch document the tag support, then a new helper function is added to v4l2-mem2mem.c to easily copy data from a source to a destination buffer that drivers can use. Next a new supports_tags vb2_queue flag is added to indicate that the driver supports tags. Ideally this should not be necessary, but that would require that all m2m drivers are converted to using the new helper function introduced in the previous patch. That takes more time then I have now since we want to get this in for 4.20. Finally the vim2m, vicodec and cedrus drivers are converted to support tags. I also removed the 'pad' fields from the mpeg2 control structs (it should never been added in the first place) and aligned the structs to a u32 boundary (u64 for the tag values). Note that this might change further (Paul suggested using bitfields). Also note that the cedrus code doesn't set the sequence counter, that's something that should still be added before this driver can be moved out of staging. Note: if no buffer is found for a certain tag, then the dma address is just set to 0. That happened before as well with invalid buffer indices. This should be checked in the driver! The previous RFC series was tested successfully with the cedrus driver. Regards, Hans Changes since v1: - changed to a u32 tag. Using a 64 bit tag was overly complicated due to the bad layout of the v4l2_buffer struct, and there is no real need for it by applications. Main changes since the RFC: - Added new buffer capability flag - Added m2m helper to copy data between buffers - Added documentation - Added tag logging in v4l2-ioctl.c Hans Verkuil (9): videodev2.h: add tag support vb2: add tag support v4l2-ioctl.c: log v4l2_buffer tag buffer.rst: document the new buffer tag feature. v4l2-mem2mem: add v4l2_m2m_buf_copy_data helper function vb2: add new supports_tags queue flag vim2m: add tag support vicodec: add tag support cedrus: add tag support Documentation/media/uapi/v4l/buffer.rst | 32 +++++++++---- .../media/uapi/v4l/vidioc-reqbufs.rst | 4 ++ .../media/common/videobuf2/videobuf2-v4l2.c | 45 ++++++++++++++++--- drivers/media/platform/vicodec/vicodec-core.c | 14 ++---- drivers/media/platform/vim2m.c | 14 ++---- drivers/media/v4l2-core/v4l2-ctrls.c | 9 ---- drivers/media/v4l2-core/v4l2-ioctl.c | 9 ++-- drivers/media/v4l2-core/v4l2-mem2mem.c | 23 ++++++++++ drivers/staging/media/sunxi/cedrus/cedrus.h | 9 ++-- .../staging/media/sunxi/cedrus/cedrus_dec.c | 2 + .../staging/media/sunxi/cedrus/cedrus_mpeg2.c | 21 ++++----- .../staging/media/sunxi/cedrus/cedrus_video.c | 2 + include/media/v4l2-mem2mem.h | 21 +++++++++ include/media/videobuf2-core.h | 2 + include/media/videobuf2-v4l2.h | 21 ++++++++- include/uapi/linux/v4l2-controls.h | 14 +++--- include/uapi/linux/videodev2.h | 9 +++- 17 files changed, 178 insertions(+), 73 deletions(-) -- 2.19.1
