media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams

The ISI crossbar needs to properly enable multiple streams from different
virtual channels on the same input pad. Currently only the first stream
gets enabled in hardware, subsequent streams are silently ignored.

The driver uses a single enable_count per input to track the input state.
When enable_count is non-zero, the code assumes the input is already active
and skips calling v4l2_subdev_enable_streams() for additional streams:

  Call 1: enable_streams(stream 0)
    -> enable_count == 0, enable gasket and stream 0 in hardware
    -> enable_count = 1

  Call 2: enable_streams(stream 1)
    -> enable_count == 1, skip hardware enable
    -> enable_count = 2
    -> stream 1 never gets enabled

Similarly on disable, when enable_count reaches zero, ALL streams are
disabled regardless of which streams are actually still active.

Implement per-stream state tracking by storing the input index and stream
mask in the mxc_isi_pipe structure. On enable, record which input and
stream the pipe is receiving. On disable, clear the pipe's record and
check if any other pipe is still using the same input stream before
actually disabling it.

Signed-off-by: Guoniu Zhou <guoniu.zhou@oss.nxp.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260728-isi-v5-2-1d22ab91602a@oss.nxp.com
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

0 files changed, 0 insertions, 0 deletions