media: v4l2-ctrls: add change flag for when dimensions change

Add a new V4L2_EVENT_CTRL_CH_DIMENSIONS change flag that is issued
when the dimensions of an array change as a result of a
__v4l2_ctrl_modify_dimensions() call.

This will inform userspace that there are new dimensions.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/userspace-api/media/v4l/vidioc-dqevent.rst

@@ -332,6 +332,11 @@ call.
       - 0x0004
       - This control event was triggered because the minimum, maximum,
 	step or the default value of the control changed.
+    * - ``V4L2_EVENT_CTRL_CH_DIMENSIONS``
+      - 0x0008
+      - This control event was triggered because the dimensions of the
+	control changed. Note that the number of dimensions remains the
+	same.
 
 
 .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|

Documentation/userspace-api/media/videodev2.h.rst.exceptions

@@ -514,6 +514,7 @@ replace define V4L2_EVENT_PRIVATE_START event-type
 replace define V4L2_EVENT_CTRL_CH_VALUE ctrl-changes-flags
 replace define V4L2_EVENT_CTRL_CH_FLAGS ctrl-changes-flags
 replace define V4L2_EVENT_CTRL_CH_RANGE ctrl-changes-flags
+replace define V4L2_EVENT_CTRL_CH_DIMENSIONS ctrl-changes-flags
 
 replace define V4L2_EVENT_SRC_CH_RESOLUTION src-changes-flags
 

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

@@ -1020,7 +1020,8 @@ int __v4l2_ctrl_modify_dimensions(struct v4l2_ctrl *ctrl,
 	for (i = 0; i < elems; i++)
 		ctrl->type_ops->init(ctrl, i, ctrl->p_cur);
 	cur_to_new(ctrl);
-	send_event(NULL, ctrl, V4L2_EVENT_CTRL_CH_VALUE);
+	send_event(NULL, ctrl, V4L2_EVENT_CTRL_CH_VALUE |
+			       V4L2_EVENT_CTRL_CH_DIMENSIONS);
 	return 0;
 }
 EXPORT_SYMBOL(__v4l2_ctrl_modify_dimensions);

include/uapi/linux/videodev2.h

@@ -2435,6 +2435,7 @@ struct v4l2_event_vsync {
 #define V4L2_EVENT_CTRL_CH_VALUE		(1 << 0)
 #define V4L2_EVENT_CTRL_CH_FLAGS		(1 << 1)
 #define V4L2_EVENT_CTRL_CH_RANGE		(1 << 2)
+#define V4L2_EVENT_CTRL_CH_DIMENSIONS		(1 << 3)
 
 struct v4l2_event_ctrl {
 	__u32 changes;