From: Hans Verkuil <hans.verkuil@xxxxxxxxx> Specify that STREAMON/OFF should return 0 if the stream is already started/stopped. The spec never specified what the correct behavior is. This ambiguity was resolved during the 2012 Media Workshop. Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> --- Documentation/DocBook/media/v4l/vidioc-streamon.xml | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/Documentation/DocBook/media/v4l/vidioc-streamon.xml b/Documentation/DocBook/media/v4l/vidioc-streamon.xml index 81cca45..716ea15 100644 --- a/Documentation/DocBook/media/v4l/vidioc-streamon.xml +++ b/Documentation/DocBook/media/v4l/vidioc-streamon.xml @@ -74,7 +74,12 @@ not transmitted yet. I/O returns to the same state as after calling stream type. This is the same as &v4l2-requestbuffers; <structfield>type</structfield>.</para> - <para>Note applications can be preempted for unknown periods right + <para>If <constant>VIDIOC_STREAMON</constant> is called when streaming +is already in progress, or if <constant>VIDIOC_STREAMOFF</constant> is called +when streaming is already stopped, then the ioctl does nothing and 0 is +returned.</para> + + <para>Note that applications can be preempted for unknown periods right before or after the <constant>VIDIOC_STREAMON</constant> or <constant>VIDIOC_STREAMOFF</constant> calls, there is no notion of starting or stopping "now". Buffer timestamps can be used to -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
