[media] v4l: Add source change event

This event indicates that the video device has encountered
a source parameter change during runtime. This can typically be a
resolution change detected by a video decoder OR a format change
detected by an input connector.

This needs to be nofified to the userspace and the application may
be expected to reallocate buffers before proceeding. The application
can subscribe to events on a specific pad or input port which
it is interested in.

Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

Documentation/DocBook/media/v4l/vidioc-dqevent.xml

@@ -242,6 +242,22 @@
       </tgroup>
     </table>
 
+    <table frame="none" pgwide="1" id="v4l2-event-src-change">
+      <title>struct <structname>v4l2_event_src_change</structname></title>
+      <tgroup cols="3">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>changes</structfield></entry>
+	    <entry>
+	      A bitmask that tells what has changed. See <xref linkend="src-changes-flags" />.
+	    </entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
     <table pgwide="1" frame="none" id="changes-flags">
       <title>Changes</title>
       <tgroup cols="3">
@@ -270,6 +286,23 @@
 	</tbody>
       </tgroup>
     </table>
+
+    <table pgwide="1" frame="none" id="src-changes-flags">
+      <title>Source Changes</title>
+      <tgroup cols="3">
+	&cs-def;
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>V4L2_EVENT_SRC_CH_RESOLUTION</constant></entry>
+	    <entry>0x0001</entry>
+	    <entry>This event gets triggered when a resolution change is
+	    detected at an input. This can come from an input connector or
+	    from a video decoder.
+	    </entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
   </refsect1>
   <refsect1>
     &return-value;

Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml

@@ -154,6 +154,26 @@
 	      frame interval in between them.</para>
 	    </entry>
 	  </row>
+	  <row>
+	    <entry><constant>V4L2_EVENT_SOURCE_CHANGE</constant></entry>
+	    <entry>5</entry>
+	    <entry>
+	      <para>This event is triggered when a source parameter change is
+	       detected during runtime by the video device. It can be a
+	       runtime resolution change triggered by a video decoder or the
+	       format change happening on an input connector.
+	       This event requires that the <structfield>id</structfield>
+	       matches the input index (when used with a video device node)
+	       or the pad index (when used with a subdevice node) from which
+	       you want to receive events.</para>
+
+              <para>This event has a &v4l2-event-source-change; associated
+	      with it. The <structfield>changes</structfield> bitfield denotes
+	      what has changed for the subscribed pad. If multiple events
+	      occurred before application could dequeue them, then the changes
+	      will have the ORed value of all the events generated.</para>
+	    </entry>
+	  </row>
 	  <row>
 	    <entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry>
 	    <entry>0x08000000</entry>