[media] v4l: Add new alpha component control

The V4L2_CID_ALPHA_COMPONENT control is intended for the video capture
or memory-to-memory devices that are capable of setting up the per-pixel
alpha component to some arbitrary value. It allows to set the alpha
component for all pixels to an arbitrary value.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

3 files changed, 35 insertions, 8 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