This control is intended for video capture or memory-to-memory
devices that are capable of setting up the alpha conponent to
some arbitrary value.
The V4L2_CID_COLOR_ALPHA control allows to set the alpha channel
globally to a value in range from 0 to 255.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
Documentation/DocBook/media/v4l/controls.xml | 20 ++++++++++++++------
.../DocBook/media/v4l/pixfmt-packed-rgb.xml | 7 +++++--
drivers/media/video/v4l2-ctrls.c | 7 +++++++
include/linux/videodev2.h | 6 +++---
4 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index 3bc5ee8..7f99222 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 +339,20 @@ 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-color-alpha">
+ <entry><constant>V4L2_CID_COLOR_ALPHA</constant></entry>
+ <entry>integer</entry>
+ <entry> Sets the color alpha component on the capture device. It is
+ applicable to any pixel formats that contain the alpha component,
+ e.g. <link linkend="rgb-formats">packed RGB image formats</link>.
+ </entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_CID_LASTP1</constant></entry>
+ <entry></entry>
+ <entry>End of the predefined control IDs (currently
+ <constant>V4L2_CID_COLOR_ALPHA</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 4db272b..da4c360 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 global alpha has been configured
+for a <link linkend="capture">Video Capture</link> by means of
+<link linkend="v4l2-color-alpha"> <constant>V4L2_CID_COLOR_ALPHA
+</constant> </link> control.</para>
<example>
<title><constant>V4L2_PIX_FMT_BGR24</constant> 4 × 4 pixel
diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index 5552f81..bd90955 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -466,6 +466,7 @@ 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_COLOR_ALPHA: return "Color Alpha";
/* MPEG controls */
/* Keep the order of the 'case's the same as in videodev2.h! */
@@ -714,6 +715,12 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
/* Max is calculated as RGB888 that is 2^24 */
*max = 0xFFFFFF;
break;
+ case V4L2_CID_COLOR_ALPHA:
+ *type = V4L2_CTRL_TYPE_INTEGER;
+ *step = 1;
+ *min = 0;
+ *max = 0xff;
+ break;
case V4L2_CID_FLASH_FAULT:
*type = V4L2_CTRL_TYPE_BITMASK;
break;
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 4b752d5..42192c1 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_COLOR_ALPHA (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)
--
1.7.7.2
--
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