V4L/DVB (11618): cx18: Convert per stream mutex locks to per queue spin locks

To avoid sleeps in providing buffers to user space and in handling incoming
buffers from the capture unit, converted the per stream mutex for locking
queues to 3 spin locks.  There is now a spin lock per queue
to increase concurrency when moving buffers around.

Also simplified queue manipulations and buffer handling of incoming buffers
of data from the capture unit.

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

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/media/video/cx18/cx18-streams.c b/drivers/media/video/cx18/cx18-streams.c
index bbeb01c5cf32..e1934e9cfdc8 100644
--- a/drivers/media/video/cx18/cx18-streams.c
+++ b/drivers/media/video/cx18/cx18-streams.c
@@ -116,11 +116,13 @@ static void cx18_stream_init(struct cx18 *cx, int type)
         s->buffers = cx->stream_buffers[type];
         s->buf_size = cx->stream_buf_size[type];
 
-        mutex_init(&s->qlock);
         init_waitqueue_head(&s->waitq);
         s->id = -1;
+        spin_lock_init(&s->q_free.lock);
         cx18_queue_init(&s->q_free);
+        spin_lock_init(&s->q_busy.lock);
         cx18_queue_init(&s->q_busy);
+        spin_lock_init(&s->q_full.lock);
         cx18_queue_init(&s->q_full);
 }
 
@@ -685,13 +687,13 @@ int cx18_start_v4l2_encode_stream(struct cx18_stream *s)
 
         /* Init all the cpu_mdls for this stream */
         cx18_flush_queues(s);
-        mutex_lock(&s->qlock);
+        spin_lock(&s->q_free.lock);
         list_for_each_entry(buf, &s->q_free.list, list) {
                 cx18_writel(cx, buf->dma_handle,
                                         &cx->scb->cpu_mdl[buf->id].paddr);
                 cx18_writel(cx, s->buf_size, &cx->scb->cpu_mdl[buf->id].length);
         }
-        mutex_unlock(&s->qlock);
+        spin_unlock(&s->q_free.lock);
         _cx18_stream_load_fw_queue(s);
 
         /* begin_capture */