[media] v4l2-ctrl: Add helper function for the controls range update

This patch adds a helper function that allows to modify range,
i.e. minimum, maximum, step and default value of a v4l2 control,
after the control has been created and initialized. This is helpful
in situations when range of a control depends on user configurable
parameters, e.g. camera sensor absolute exposure time depending on
an output image resolution and frame rate.
v4l2_ctrl_modify_range() function allows to modify range of an
INTEGER, BOOL, MENU, INTEGER_MENU and BITMASK type controls.
Based on a patch from Hans Verkuil http://patchwork.linuxtv.org/patch/8654.

Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index ebd2bfd..104a1a2 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2486,6 +2486,10 @@
 	  <structname>v4l2_buffer</structname>. See <xref
 	  linkend="buffer-flags" />.</para>
         </listitem>
+        <listitem>
+	  <para>Added <constant>V4L2_EVENT_CTRL_CH_RANGE</constant> control event
+	  changes flag. See <xref linkend="changes-flags"/>.</para>
+        </listitem>
       </orderedlist>
     </section>
 
diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml
index 8fe2942..c3851a2 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -142,10 +142,12 @@
       <revision>
 	<revnumber>3.9</revnumber>
 	<date>2012-12-03</date>
-	<authorinitials>sa</authorinitials>
+	<authorinitials>sa, sn</authorinitials>
 	<revremark>Added timestamp types to
 	<structname>v4l2_buffer</structname>, see <xref
 	linkend="buffer-flags" />.
+	Added <constant>V4L2_EVENT_CTRL_CH_RANGE</constant> control
+	event changes flag, see <xref linkend="changes-flags"/>.
 	</revremark>
       </revision>
 
diff --git a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
index 98a856f..89891ad 100644
--- a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
@@ -261,6 +261,12 @@
 	    <entry>This control event was triggered because the control flags
 		changed.</entry>
 	  </row>
+	  <row>
+	    <entry><constant>V4L2_EVENT_CTRL_CH_RANGE</constant></entry>
+	    <entry>0x0004</entry>
+	    <entry>This control event was triggered because the minimum,
+	    maximum, step or the default value of the control changed.</entry>
+	  </row>
 	</tbody>
       </tgroup>
     </table>