V4L/DVB (9720): cx18: Major rewrite of interrupt handling for incoming mailbox processing

A major rewrite of interrupt handling for incoming mailbox processing, to split
the timing critical steps from the the deferrable steps as the sending XPU on
the CX23418 will time out and overwrite our incoming mailboxes rather quickly.
Setup a pool of work "order forms" for the irq handler to send jobs to the new
work handler routine which uses the kernel default work queue to do the
deferrable work.  Started optimizing some of the cx18-io calls as they are now
the low hanging fruit for recoving microseconds back from the timeline.
Future optimizations will get rid of mmio read retries, mmio stats logging, and
combine smaller functions in the irq path into the larger ones to save ~2 us
each.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/media/video/cx18/cx18-streams.c b/drivers/media/video/cx18/cx18-streams.c
index c7d431f4923..e6d808f7cc8 100644
--- a/drivers/media/video/cx18/cx18-streams.c
+++ b/drivers/media/video/cx18/cx18-streams.c
@@ -595,3 +595,21 @@ u32 cx18_find_handle(struct cx18 *cx)
 	}
 	return CX18_INVALID_TASK_HANDLE;
 }
+
+struct cx18_stream *cx18_handle_to_stream(struct cx18 *cx, u32 handle)
+{
+	int i;
+	struct cx18_stream *s;
+
+	if (handle == CX18_INVALID_TASK_HANDLE)
+		return NULL;
+
+	for (i = 0; i < CX18_MAX_STREAMS; i++) {
+		s = &cx->streams[i];
+		if (s->handle != handle)
+			continue;
+		if (s->v4l2dev || s->dvb.enabled)
+			return s;
+	}
+	return NULL;
+}