v4l2_ctrl_grab — Mark the control as grabbed or not grabbed.
|struct v4l2_ctrl * ctrl,|
This sets or clears the V4L2_CTRL_FLAG_GRABBED flag atomically.
Does nothing if
ctrl == NULL.
The V4L2_EVENT_CTRL event will be generated afterwards.
This will usually be called when starting or stopping streaming in the
This function assumes that the control handler is not locked and will take the lock itself.