To gain better control of when a file descriptor is open to the media device and reduce the work needed in pipeline handler implementations, handle the file descriptor in acquire() and release(). This changes the current behavior where a file descriptor is only open when requested by the pipeline handler to that one is always open as long a media device is acquired. This new behavior is desired to allow implementing exclusive access to a pipeline handler between processes. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>