[media] v4l: add V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME

Some drivers also need a control like
V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE to force an encoder
key frame. Add a general V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME
so the new drivers and applications can use it.

Signed-off-by: Wu-Cheng Li <wuchengli@chromium.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Documentation/DocBook/media/v4l/controls.xml

@@ -2329,6 +2329,14 @@ to search and match for the present Macroblock (MB) in the reference picture. Th
 vertical search range for motion estimation module in video encoder.</entry>
 	      </row>
 
+	      <row><entry></entry></row>
+	      <row id="v4l2-mpeg-video-force-key-frame">
+		<entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME</constant>&nbsp;</entry>
+		<entry>button</entry>
+	      </row><row><entry spanname="descr">Force a key frame for the next queued buffer. Applicable to encoders.
+This is a general, codec-agnostic keyframe control.</entry>
+	      </row>
+
 	      <row><entry></entry></row>
 	      <row>
 		<entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE</constant>&nbsp;</entry>

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

@@ -758,6 +758,7 @@ const char *v4l2_ctrl_get_name(u32 id)
 	case V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE:		return "Horizontal MV Search Range";
 	case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE:		return "Vertical MV Search Range";
 	case V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER:		return "Repeat Sequence Header";
+	case V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME:		return "Force Key Frame";
 
 	/* VPX controls */
 	case V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS:		return "VPX Number of Partitions";
@@ -998,6 +999,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
 	case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE:
 		*type = V4L2_CTRL_TYPE_INTEGER;
 		break;
+	case V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME:
 	case V4L2_CID_PAN_RESET:
 	case V4L2_CID_TILT_RESET:
 	case V4L2_CID_FLASH_STROBE:

include/uapi/linux/v4l2-controls.h

@@ -390,6 +390,7 @@ enum v4l2_mpeg_video_multi_slice_mode {
 #define V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER		(V4L2_CID_MPEG_BASE+226)
 #define V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE		(V4L2_CID_MPEG_BASE+227)
 #define V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE		(V4L2_CID_MPEG_BASE+228)
+#define V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME		(V4L2_CID_MPEG_BASE+229)
 
 #define V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP		(V4L2_CID_MPEG_BASE+300)
 #define V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP		(V4L2_CID_MPEG_BASE+301)