MIPI-CSI has internal memory mapped buffers for the frame embedded
(non-image) data. There are two buffers, for even and odd frames which
need to be saved after an interrupt is raised. The packet data buffers
size is 4 KiB and there is no status register in the hardware where the
actual non-image data size can be read from. Hence the driver copies
whole packet data buffer into a buffer provided by the FIMC driver.
This will form a separate plane in the user buffer.
When FIMC DMA engine is stopped by the driver due the to user space
not keeping up with buffer de-queuing the MIPI-CSIS will still run,
however it must discard data which is not captured by FIMC. Which
frames are actually capture by MIPI-CSIS is determined by means of
the s_tx_buffer subdev callback. When it is not called after a single
embedded data frame has been captured and copied and before next
embedded data frame interrupt occurrs, subsequent embedded data frames
will be dropped.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>