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-rw-r--r--Documentation/DocBook/media/v4l/vidioc-queryctrl.xml9
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-queryctrl.xml b/Documentation/DocBook/media/v4l/vidioc-queryctrl.xml
index 677ea646c29..0ac0057a51c 100644
--- a/Documentation/DocBook/media/v4l/vidioc-queryctrl.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-queryctrl.xml
@@ -406,6 +406,15 @@ flag is typically present for relative controls or action controls where
writing a value will cause the device to carry out a given action
(&eg; motor control) but no meaningful value can be returned.</entry>
</row>
+ <row>
+ <entry><constant>V4L2_CTRL_FLAG_VOLATILE</constant></entry>
+ <entry>0x0080</entry>
+ <entry>This control is volatile, which means that the value of the control
+changes continuously. A typical example would be the current gain value if the device
+is in auto-gain mode. In such a case the hardware calculates the gain value based on
+the lighting conditions which can change over time. Note that setting a new value for
+a volatile control will have no effect. The new value will just be ignored.</entry>
+ </row>
</tbody>
</tgroup>
</table>