[media] v4l: Add subdev selections documentation

Add documentation for V4L2 subdev selection API. This changes also
experimental V4L2 subdev API so that scaling now works through selection API
only.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.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 d881520..0fc74ca 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2417,6 +2417,11 @@
 	  <para>Added integer menus, the new type will be
 	  V4L2_CTRL_TYPE_INTEGER_MENU.</para>
         </listitem>
+        <listitem>
+	  <para>Added selection API for V4L2 subdev interface:
+	  &VIDIOC-SUBDEV-G-SELECTION; and
+	  &VIDIOC-SUBDEV-S-SELECTION;.</para>
+        </listitem>
       </orderedlist>
     </section>
 
@@ -2533,6 +2538,10 @@
         <listitem>
 	  <para>Selection API. <xref linkend="selection-api" /></para>
         </listitem>
+        <listitem>
+	  <para>Sub-device selection API: &VIDIOC-SUBDEV-G-SELECTION;
+	  and &VIDIOC-SUBDEV-S-SELECTION; ioctls.</para>
+        </listitem>
       </itemizedlist>
     </section>