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-rw-r--r--Documentation/DocBook/media/v4l/vidioc-streamon.xml7
1 files changed, 6 insertions, 1 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-streamon.xml b/Documentation/DocBook/media/v4l/vidioc-streamon.xml
index 81cca4569050..716ea15e54a1 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
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