On Wed, Nov 14, 2018 at 10:47 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > > 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 Good call on the v4l2_m2m_buf_copy_data() function! Reviewed-by: Alexandre Courbot <acourbot@xxxxxxxxxxxx> > > 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 >
