Please don't do that
I reply the
Re: [PATCHv4 00/10] As was discussed here (among other places):
talking about the disadvantage of using the buffer tag, driver won't
aware which buffer will be used for current picture unless all the
previous work are done.
On 1/7/19 7:36 PM, Hans Verkuil wrote:
On 01/07/2019 12:30 PM, Hans Verkuil wrote:
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.
Instead, after a long irc discussion:
https://linuxtv.org/irc/irclogger_log/v4l?date=2018-12-12,Wed
it was decided to use the timestamp in v4l2_buffer for this.
However, struct timeval cannot be used in a compound control since
the size of struct timeval differs between 32 and 64 bit architectures,
and there are also changes upcoming for y2038 support.
But internally the kernel converts the timeval to a u64 (nsecs since
boot). So we provide a helper function in videodev2.h that converts
the timeval to a u64, and that u64 can be used inside compound controls.
In the not too distant future we want to create a new struct v4l2_buffer,
and then we'll use u64 from the start, so in that case the helper function
would no longer be needed.
The first three patches add a new m2m helper function to correctly copy
the relevant data from an output buffer to a capture buffer. This will
simplify m2m drivers (in fact, many m2m drivers do not do this quite
right, so a helper function was really needed).
The fourth patch clears up messy timecode documentation that I came
across while working on this.
Patch 5 adds the new v4l2_timeval_to_ns helper function to videodev2.h.
The next patch adds the vb2_find_timestamp() function to find buffers
with a specific u64 timestamp.
Finally the cedrus driver and documentation are updated to use a
timestamp as buffer identifier.
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.
Note that this pull request corresponds with the v6 patch series.
("[PATCHv6 0/8] vb2/cedrus: use timestamps to identify buffers")
Regards,
Hans
Regards,
Hans
The following changes since commit 4bd46aa0353e022c2401a258e93b107880a66533:
media: cx23885: only reset DMA on problematic CPUs (2018-12-20 06:52:01 -0500)
are available in the Git repository at:
git://linuxtv.org/hverkuil/media_tree.git tags/br-buftag
for you to fetch changes up to 690da7b0ab96f6761e72bb0c5c861e1e13acb327:
extended-controls.rst: update the mpeg2 compound controls (2019-01-07 12:23:49 +0100)
----------------------------------------------------------------
Tag branch
----------------------------------------------------------------
Hans Verkuil (8):
v4l2-mem2mem: add v4l2_m2m_buf_copy_data helper function
vim2m: use v4l2_m2m_buf_copy_data
vicodec: use v4l2_m2m_buf_copy_data
buffer.rst: clean up timecode documentation
videodev2.h: add v4l2_timeval_to_ns inline function
vb2: add vb2_find_timestamp()
cedrus: identify buffers by timestamp
extended-controls.rst: update the mpeg2 compound controls
Documentation/media/uapi/v4l/buffer.rst | 11 +++++------
Documentation/media/uapi/v4l/extended-controls.rst | 28 +++++++++++++++++-----------
drivers/media/common/videobuf2/videobuf2-v4l2.c | 19 ++++++++++++++++++-
drivers/media/platform/vicodec/vicodec-core.c | 12 +-----------
drivers/media/platform/vim2m.c | 12 +-----------
drivers/media/v4l2-core/v4l2-ctrls.c | 9 ---------
drivers/media/v4l2-core/v4l2-mem2mem.c | 20 ++++++++++++++++++++
drivers/staging/media/sunxi/cedrus/cedrus.h | 9 ++++++---
drivers/staging/media/sunxi/cedrus/cedrus_dec.c | 2 ++
drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c | 23 +++++++++++------------
include/media/mpeg2-ctrls.h | 14 +++++---------
include/media/v4l2-mem2mem.h | 20 ++++++++++++++++++++
include/media/videobuf2-v4l2.h | 17 +++++++++++++++++
include/uapi/linux/videodev2.h | 12 ++++++++++++
14 files changed, 135 insertions(+), 73 deletions(-)
