[media] v4l: events: Define V4L2_EVENT_FRAME_SYNC

Define a frame sync event to tell user space when the reception of a frame
starts.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index fca24cc..a5359c6 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -2006,6 +2006,7 @@
 #define V4L2_EVENT_VSYNC			1
 #define V4L2_EVENT_EOS				2
 #define V4L2_EVENT_CTRL				3
+#define V4L2_EVENT_FRAME_SYNC			4
 #define V4L2_EVENT_PRIVATE_START		0x08000000
 
 /* Payload for V4L2_EVENT_VSYNC */
@@ -2032,12 +2033,17 @@
 	__s32 default_value;
 };
 
+struct v4l2_event_frame_sync {
+	__u32 frame_sequence;
+};
+
 struct v4l2_event {
 	__u32				type;
 	union {
-		struct v4l2_event_vsync vsync;
-		struct v4l2_event_ctrl	ctrl;
-		__u8			data[64];
+		struct v4l2_event_vsync		vsync;
+		struct v4l2_event_ctrl		ctrl;
+		struct v4l2_event_frame_sync	frame_sync;
+		__u8				data[64];
 	} u;
 	__u32				pending;
 	__u32				sequence;