5 files changed, 39 insertions, 11 deletions

diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index 8b44a43f4542..12ba26262d32 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2379,6 +2379,17 @@ that used it. It was originally scheduled for removal in 2.6.35.
       </orderedlist>
     </section>
 
+    <section>
+      <title>V4L2 in Linux 3.3</title>
+      <orderedlist>
+        <listitem>
+          <para>Added <constant>V4L2_CID_ALPHA_COMPONENT</constant> control
+            to the <link linkend="control">User controls class</link>.
+          </para>
+        </listitem>
+      </orderedlist>
+    </section>
+
     <section id="other">
       <title>Relation of V4L2 to other Linux multimedia APIs</title>
 
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index c0422c622337..a1be37897ad7 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -324,12 +324,6 @@ minimum value disables backlight compensation.</entry>
                 (usually a microscope).</entry>
           </row>
           <row>
-            <entry><constant>V4L2_CID_LASTP1</constant></entry>
-            <entry></entry>
-            <entry>End of the predefined control IDs (currently
-<constant>V4L2_CID_ILLUMINATORS_2</constant> + 1).</entry>
-          </row>
-          <row>
             <entry><constant>V4L2_CID_MIN_BUFFERS_FOR_CAPTURE</constant></entry>
             <entry>integer</entry>
             <entry>This is a read-only control that can be read by the application
@@ -345,6 +339,25 @@ and used as a hint to determine the number of OUTPUT buffers to pass to REQBUFS.
 The value is the minimum number of OUTPUT buffers that is necessary for hardware
 to work.</entry>
           </row>
+          <row id="v4l2-alpha-component">
+            <entry><constant>V4L2_CID_ALPHA_COMPONENT</constant></entry>
+            <entry>integer</entry>
+            <entry> Sets the alpha color component on the capture device or on
+            the capture buffer queue of a mem-to-mem device. When a mem-to-mem
+            device produces frame format that includes an alpha component
+            (e.g. <link linkend="rgb-formats">packed RGB image formats</link>)
+            and the alpha value is not defined by the mem-to-mem input data
+            this control lets you select the alpha component value of all
+            pixels. It is applicable to any pixel format that contains an alpha
+            component.
+            </entry>
+          </row>
+          <row>
+            <entry><constant>V4L2_CID_LASTP1</constant></entry>
+            <entry></entry>
+            <entry>End of the predefined control IDs (currently
+              <constant>V4L2_CID_ALPHA_COMPONENT</constant> + 1).</entry>
+          </row>
           <row>
             <entry><constant>V4L2_CID_PRIVATE_BASE</constant></entry>
             <entry></entry>
diff --git a/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml b/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
index ba56536622f2..166c8d65e4f7 100644
--- a/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
+++ b/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
@@ -428,8 +428,11 @@ colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para>
     <para>Bit 7 is the most significant bit. The value of a = alpha
 bits is undefined when reading from the driver, ignored when writing
 to the driver, except when alpha blending has been negotiated for a
-<link linkend="overlay">Video Overlay</link> or <link
-linkend="osd">Video Output Overlay</link>.</para>
+<link linkend="overlay">Video Overlay</link> or <link linkend="osd">
+Video Output Overlay</link> or when alpha component has been configured
+for a <link linkend="capture">Video Capture</link> by means of <link
+linkend="v4l2-alpha-component"> <constant>V4L2_CID_ALPHA_COMPONENT
+</constant> </link> control.</para>
 
     <example>
       <title><constant>V4L2_PIX_FMT_BGR24</constant> 4 &times; 4 pixel
diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index 0f415dade05a..39266153499f 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -467,6 +467,7 @@ const char *v4l2_ctrl_get_name(u32 id)
         case V4L2_CID_ILLUMINATORS_2:           return "Illuminator 2";
         case V4L2_CID_MIN_BUFFERS_FOR_CAPTURE:  return "Minimum Number of Capture Buffers";
         case V4L2_CID_MIN_BUFFERS_FOR_OUTPUT:   return "Minimum Number of Output Buffers";
+        case V4L2_CID_ALPHA_COMPONENT:          return "Alpha Component";
 
         /* MPEG controls */
         /* Keep the order of the 'case's the same as in videodev2.h! */
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 3d62631839bc..2965906a02c9 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -1204,10 +1204,10 @@ enum v4l2_colorfx {
 #define V4L2_CID_MIN_BUFFERS_FOR_CAPTURE        (V4L2_CID_BASE+39)
 #define V4L2_CID_MIN_BUFFERS_FOR_OUTPUT         (V4L2_CID_BASE+40)
 
-/* last CID + 1 */
-#define V4L2_CID_LASTP1                         (V4L2_CID_BASE+41)
+#define V4L2_CID_ALPHA_COMPONENT                (V4L2_CID_BASE+41)
 
-/* Minimum number of buffer neede by the device */
+/* last CID + 1 */
+#define V4L2_CID_LASTP1                         (V4L2_CID_BASE+42)
 
 /*  MPEG-class control IDs defined by V4L2 */
 #define V4L2_CID_MPEG_BASE                      (V4L2_CTRL_CLASS_MPEG | 0x900)