1ef323df29
When client queued a buffer, v4l2 framework compares the client Dmabuf with the existing dmabuf in the bufs array at the same index. If the dmabuf is different then v4l2 framework would call unmap_dmabuf, detach_dmabuf callbacks for the old buffer and then calls attach_dmabuf, map_dmabuf callbacks for the new buffer before qbuf callback is made to driver. If the dmabuf is same then qbuf callback will be made directly. V4l2 framework expects that clients recycles the same buffers in the same indices so that when v4l2 framework compares dmabuf it won't unmap or map buffers. If client recycle the buffers in different indices still usecase works but there will be unnecessary unmap, map overhead will be incurred. If client does not recycle the buffers at all, meaning every time client queues new buffers then special handling is required for decoder output buffers which are used for reference by video hardware.If any buffers are used by video hardware as reference buffers then firmware returns those buffers with READ_ONLY flag and they are kept in read_only list and when read_only grows beyond some limit then driver would ask firmware to release those READ_ONLY buffers and when firmware responds driver would delete these READ_ONLY buffers. Change-Id: I8a0b11c986dd0b9464895498efd8c1831a754198 Signed-off-by: Darshana Patil <quic_darshana@quicinc.com>