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[media] v4l: Add timestamp source flags, mask and document them

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Some devices do not produce timestamps that correspond to the end of the
frame. The user space should be informed on the matter. This patch achieves
that by adding buffer flags (and a mask) for timestamp sources since more
possible timestamping points are expected than just two.

A three-bit mask is defined (V4L2_BUF_FLAG_TSTAMP_SRC_MASK) and two of the
eight possible values is are defined V4L2_BUF_FLAG_TSTAMP_SRC_EOF for end of
frame (value zero) V4L2_BUF_FLAG_TSTAMP_SRC_SOE for start of exposure (next
value).

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Kamil Debski <k.debski@samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Sakari Ailus 2013-08-25 17:57:03 -03:00 • committed by Mauro Carvalho Chehab
commit 872484ce40
4 changed files with 39 additions and 7 deletions
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4
include/uapi/linux/videodev2.h
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@ -700,6 +700,10 @@ struct v4l2_buffer {
#define V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN 0x00000000
#define V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC 0x00002000
#define V4L2_BUF_FLAG_TIMESTAMP_COPY 0x00004000
/* Timestamp sources. */
#define V4L2_BUF_FLAG_TSTAMP_SRC_MASK 0x00070000
#define V4L2_BUF_FLAG_TSTAMP_SRC_EOF 0x00000000
#define V4L2_BUF_FLAG_TSTAMP_SRC_SOE 0x00010000
/**
* struct v4l2_exportbuffer - export of video buffer as DMABUF file descriptor