The camera may in some conditions incorrectly determine the exposure,
and a manual automatic exposure correction may be needed. This patch
adds V4L2_CID_AUTO_EXPOSURE_BIAS control which allows to add some
offset in the automatic exposure control loop, to compensate for
frame under- or over-exposure.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
Documentation/DocBook/media/v4l/controls.xml | 16 ++++++++++++++++
drivers/media/video/v4l2-ctrls.c | 4 ++++
include/linux/videodev2.h | 2 ++
3 files changed, 22 insertions(+)
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index fadc0a6..40e6485 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -2849,6 +2849,22 @@ remain constant.</entry>
<row><entry></entry></row>
<row>
+ <entry spanname="id"><constant>V4L2_CID_EXPOSURE_BIAS</constant> </entry>
+ <entry>integer menu</entry>
+ </row><row><entry spanname="descr"> Determines the automatic
+exposure compensation, it is effective only when <constant>V4L2_CID_EXPOSURE_AUTO</constant>
+control is set to <constant>AUTO</constant>, <constant>SHUTTER_PRIORITY </constant>
+or <constant>APERTURE_PRIORITY</constant>.
+It is expressed in terms of EV, drivers should interpret the values as 0.001 EV
+units, where the value 1000 stands for +1 EV.
+<para>Increasing the exposure compensation value is equivalent to decreasing
+the exposure value (EV) and will increase the amount of light at the image
+sensor. The camera performs the exposure compensation by adjusting absolute
+exposure time and/or aperture.</para></entry>
+ </row>
+ <row><entry></entry></row>
+
+ <row>
<entry spanname="id"><constant>V4L2_CID_PAN_RELATIVE</constant> </entry>
<entry>integer</entry>
</row><row><entry spanname="descr">This control turns the
diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index 1bc8791..4157d4c 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -604,6 +604,7 @@ const char *v4l2_ctrl_get_name(u32 id)
case V4L2_CID_PRIVACY: return "Privacy";
case V4L2_CID_IRIS_ABSOLUTE: return "Iris, Absolute";
case V4L2_CID_IRIS_RELATIVE: return "Iris, Relative";
+ case V4L2_CID_AUTO_EXPOSURE_BIAS: return "Auto Exposure, Bias";
/* FM Radio Modulator control */
/* Keep the order of the 'case's the same as in videodev2.h! */
@@ -746,6 +747,9 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
case V4L2_CID_RDS_TX_RADIO_TEXT:
*type = V4L2_CTRL_TYPE_STRING;
break;
+ case V4L2_CID_AUTO_EXPOSURE_BIAS:
+ *type = V4L2_CTRL_TYPE_INTEGER_MENU;
+ break;
case V4L2_CID_USER_CLASS:
case V4L2_CID_CAMERA_CLASS:
case V4L2_CID_MPEG_CLASS:
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index becb2ed..8b174dc 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -1700,6 +1700,8 @@ enum v4l2_exposure_auto_type {
#define V4L2_CID_IRIS_ABSOLUTE (V4L2_CID_CAMERA_CLASS_BASE+17)
#define V4L2_CID_IRIS_RELATIVE (V4L2_CID_CAMERA_CLASS_BASE+18)
+#define V4L2_CID_AUTO_EXPOSURE_BIAS (V4L2_CID_CAMERA_CLASS_BASE+19)
+
/* FM Modulator class control IDs */
#define V4L2_CID_FM_TX_CLASS_BASE (V4L2_CTRL_CLASS_FM_TX | 0x900)
#define V4L2_CID_FM_TX_CLASS (V4L2_CTRL_CLASS_FM_TX | 1)
--
1.7.10
--
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