[media] v4l: Add premultiplied alpha flag for pixel formats

When set, the new V4L2_PIX_FMT_FLAG_PREMUL_ALPHA flag indicates that the
pixel values are premultiplied by the alpha channel value.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

Documentation/DocBook/media/v4l/pixfmt.xml

@@ -135,6 +135,12 @@ extended fields were set to zero. On return drivers must set the
 <constant>V4L2_PIX_FMT_PRIV_MAGIC</constant> and all the extended fields to
 applicable values.</para></entry>
 	</row>
+	<row>
+	  <entry>__u32</entry>
+	  <entry><structfield>flags</structfield></entry>
+	    <entry>Flags set by the application or driver, see <xref
+linkend="format-flags" />.</entry>
+	</row>
       </tbody>
     </tgroup>
   </table>
@@ -222,7 +228,13 @@ codes can be used.</entry>
         </row>
 	<row>
 	  <entry>__u8</entry>
-          <entry><structfield>reserved[11]</structfield></entry>
+	  <entry><structfield>flags</structfield></entry>
+	  <entry>Flags set by the application or driver, see <xref
+linkend="format-flags" />.</entry>
+	</row>
+        <row>
+          <entry>__u8</entry>
+          <entry><structfield>reserved[10]</structfield></entry>
           <entry>Reserved for future extensions. Should be zeroed by the
            application.</entry>
         </row>
@@ -1079,4 +1091,21 @@ concatenated to form the JPEG stream. </para>
 	</tbody>
       </tgroup>
     </table>
+
+    <table frame="none" pgwide="1" id="format-flags">
+      <title>Format Flags</title>
+      <tgroup cols="3">
+	&cs-def;
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>V4L2_PIX_FMT_FLAG_PREMUL_ALPHA</constant></entry>
+	    <entry>0x00000001</entry>
+	    <entry>The color values are premultiplied by the alpha channel
+value. For example, if a light blue pixel with 50% transparency was described by
+RGBA values (128, 192, 255, 128), the same pixel described with premultiplied
+colors would be described by RGBA values (64, 96, 128, 128) </entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
   </section>

Documentation/DocBook/media/v4l/v4l2.xml

@@ -155,7 +155,7 @@ applications. -->
 	<revnumber>3.16</revnumber>
 	<date>2014-05-27</date>
 	<authorinitials>lp</authorinitials>
-	<revremark>Extended &v4l2-pix-format;.
+	<revremark>Extended &v4l2-pix-format;. Added format flags.
 	</revremark>
       </revision>
 

drivers/media/v4l2-core/v4l2-ioctl.c

@@ -256,7 +256,8 @@ static void v4l_print_format(const void *arg, bool write_only)
 		pix = &p->fmt.pix;
 		pr_cont(", width=%u, height=%u, "
 			"pixelformat=%c%c%c%c, field=%s, "
-			"bytesperline=%u, sizeimage=%u, colorspace=%d\n",
+			"bytesperline=%u, sizeimage=%u, colorspace=%d, "
+			"flags %u\n",
 			pix->width, pix->height,
 			(pix->pixelformat & 0xff),
 			(pix->pixelformat >>  8) & 0xff,
@@ -264,7 +265,7 @@ static void v4l_print_format(const void *arg, bool write_only)
 			(pix->pixelformat >> 24) & 0xff,
 			prt_names(pix->field, v4l2_field_names),
 			pix->bytesperline, pix->sizeimage,
-			pix->colorspace);
+			pix->colorspace, pix->flags);
 		break;
 	case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
 	case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:

include/uapi/linux/videodev2.h

@@ -288,6 +288,7 @@ struct v4l2_pix_format {
 	__u32          		sizeimage;
 	__u32			colorspace;	/* enum v4l2_colorspace */
 	__u32			priv;		/* private data, depends on pixelformat */
+	__u32			flags;		/* format flags (V4L2_PIX_FMT_FLAG_*) */
 };
 
 /*      Pixel format         FOURCC                          depth  Description  */
@@ -452,6 +453,9 @@ struct v4l2_pix_format {
 /* priv field value to indicates that subsequent fields are valid. */
 #define V4L2_PIX_FMT_PRIV_MAGIC		0xfeedcafe
 
+/* Flags */
+#define V4L2_PIX_FMT_FLAG_PREMUL_ALPHA	0x00000001
+
 /*
  *	F O R M A T   E N U M E R A T I O N
  */
@@ -1754,6 +1758,7 @@ struct v4l2_plane_pix_format {
  * @colorspace:		enum v4l2_colorspace; supplemental to pixelformat
  * @plane_fmt:		per-plane information
  * @num_planes:		number of planes for this format
+ * @flags:		format flags (V4L2_PIX_FMT_FLAG_*)
  */
 struct v4l2_pix_format_mplane {
 	__u32				width;
@@ -1764,7 +1769,8 @@ struct v4l2_pix_format_mplane {
 
 	struct v4l2_plane_pix_format	plane_fmt[VIDEO_MAX_PLANES];
 	__u8				num_planes;
-	__u8				reserved[11];
+	__u8				flags;
+	__u8				reserved[10];
 } __attribute__ ((packed));
 
 /**