[media] DocBook: improve STREAMON/OFF documentation

[sfrench/cifs-2.6.git] / Documentation / DocBook / media / v4l / vidioc-streamon.xml

diff --git a/Documentation/DocBook/media/v4l/vidioc-streamon.xml b/Documentation/DocBook/media/v4l/vidioc-streamon.xml
index 81cca4569050da8d789dc68973798b69fdbc8a35..716ea15e54a174be6321f19aa4be69fe00487f28 100644 (file)
--- 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