Define video buffer flags for different timestamp types. Everything up to
now have used either realtime clock or monotonic clock, without a way to
tell which clock the timestamp was taken from.
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxx>
Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
Documentation/DocBook/media/v4l/io.xml | 25 +++++++++++++++++++++++++
include/uapi/linux/videodev2.h | 4 ++++
2 files changed, 29 insertions(+), 0 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml
index 7e2f3d7..d598f2c 100644
--- a/Documentation/DocBook/media/v4l/io.xml
+++ b/Documentation/DocBook/media/v4l/io.xml
@@ -938,6 +938,31 @@ Typically applications shall use this flag for output buffers if the data
in this buffer has not been created by the CPU but by some DMA-capable unit,
in which case caches have not been used.</entry>
</row>
+ <row>
+ <entry><constant>V4L2_BUF_FLAG_TIMESTAMP_MASK</constant></entry>
+ <entry>0xe000</entry>
+ <entry>Mask for timestamp types below. To test the
+ timestamp type, mask out bits not belonging to timestamp
+ type by performing a logical and operation with buffer
+ flags and timestamp mask.</tt> </entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN</constant></entry>
+ <entry>0x0000</entry>
+ <entry>Unknown timestamp type. This type is used by
+ drivers before Linux 3.8 and may be either monotonic (see
+ below) or realtime. Monotonic clock has been favoured in
+ embedded systems whereas most of the drivers use the
+ realtime clock.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC</constant></entry>
+ <entry>0x2000</entry>
+ <entry>The buffer timestamp has been taken from the
+ <constant>CLOCK_MONOTONIC</constant> clock. To access the
+ same clock outside V4L2, use <tt>clock_gettime(2)</tt>
+ .</entry>
+ </row>
</tbody>
</tgroup>
</table>
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 2fff7ff..410ea9f 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -686,6 +686,10 @@ struct v4l2_buffer {
/* Cache handling flags */
#define V4L2_BUF_FLAG_NO_CACHE_INVALIDATE 0x0800
#define V4L2_BUF_FLAG_NO_CACHE_CLEAN 0x1000
+/* Timestamp type */
+#define V4L2_BUF_FLAG_TIMESTAMP_MASK 0xe000
+#define V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN 0x0000
+#define V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC 0x2000
/*
* O V E R L A Y P R E V I E W
--
1.7.2.5
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