[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>

3 files changed, 13 insertions, 1 deletions

diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index ebd2bfd1ee8e..104a1a2b8849 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2486,6 +2486,10 @@ that used it. It was originally scheduled for removal in 2.6.35.
           <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 8fe29427c8e4..c3851a2fb50d 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -142,10 +142,12 @@ applications. -->
       <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 98a856f9ec30..89891adb928a 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>