1 files changed, 51 insertions, 34 deletions

diff --git a/drivers/media/video/cx18/cx18-queue.c b/drivers/media/video/cx18/cx18-queue.c
index 3046b8e74345..fa1ed7897d97 100644
--- a/drivers/media/video/cx18/cx18-queue.c
+++ b/drivers/media/video/cx18/cx18-queue.c
@@ -23,8 +23,8 @@
  */
 
 #include "cx18-driver.h"
-#include "cx18-streams.h"
 #include "cx18-queue.h"
+#include "cx18-streams.h"
 #include "cx18-scb.h"
 
 void cx18_buf_swap(struct cx18_buffer *buf)
@@ -53,13 +53,13 @@ struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
                 buf->skipped = 0;
         }
 
-        mutex_lock(&s->qlock);
-
         /* q_busy is restricted to a max buffer count imposed by firmware */
         if (q == &s->q_busy &&
             atomic_read(&q->buffers) >= CX18_MAX_FW_MDLS_PER_STREAM)
                 q = &s->q_free;
 
+        spin_lock(&q->lock);
+
         if (to_front)
                 list_add(&buf->list, &q->list); /* LIFO */
         else
@@ -67,7 +67,7 @@ struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
         q->bytesused += buf->bytesused - buf->readpos;
         atomic_inc(&q->buffers);
 
-        mutex_unlock(&s->qlock);
+        spin_unlock(&q->lock);
         return q;
 }
 
@@ -75,7 +75,7 @@ struct cx18_buffer *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q)
 {
         struct cx18_buffer *buf = NULL;
 
-        mutex_lock(&s->qlock);
+        spin_lock(&q->lock);
         if (!list_empty(&q->list)) {
                 buf = list_first_entry(&q->list, struct cx18_buffer, list);
                 list_del_init(&buf->list);
@@ -83,7 +83,7 @@ struct cx18_buffer *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q)
                 buf->skipped = 0;
                 atomic_dec(&q->buffers);
         }
-        mutex_unlock(&s->qlock);
+        spin_unlock(&q->lock);
         return buf;
 }
 
@@ -94,9 +94,23 @@ struct cx18_buffer *cx18_queue_get_buf(struct cx18_stream *s, u32 id,
         struct cx18_buffer *buf;
         struct cx18_buffer *tmp;
         struct cx18_buffer *ret = NULL;
-
-        mutex_lock(&s->qlock);
+        LIST_HEAD(sweep_up);
+
+        /*
+         * We don't have to acquire multiple q locks here, because we are
+         * serialized by the single threaded work handler.
+         * Buffers from the firmware will thus remain in order as
+         * they are moved from q_busy to q_full or to the dvb ring buffer.
+         */
+        spin_lock(&s->q_busy.lock);
         list_for_each_entry_safe(buf, tmp, &s->q_busy.list, list) {
+                /*
+                 * We should find what the firmware told us is done,
+                 * right at the front of the queue.  If we don't, we likely have
+                 * missed a buffer done message from the firmware.
+                 * Once we skip a buffer repeatedly, relative to the size of
+                 * q_busy, we have high confidence we've missed it.
+                 */
                 if (buf->id != id) {
                         buf->skipped++;
                         if (buf->skipped >= atomic_read(&s->q_busy.buffers)-1) {
@@ -105,38 +119,41 @@ struct cx18_buffer *cx18_queue_get_buf(struct cx18_stream *s, u32 id,
                                           "times - it must have dropped out of "
                                           "rotation\n", s->name, buf->id,
                                           buf->skipped);
-                                /* move it to q_free */
-                                list_move_tail(&buf->list, &s->q_free.list);
-                                buf->bytesused = buf->readpos = buf->b_flags =
-                                        buf->skipped = 0;
+                                /* Sweep it up to put it back into rotation */
+                                list_move_tail(&buf->list, &sweep_up);
                                 atomic_dec(&s->q_busy.buffers);
-                                atomic_inc(&s->q_free.buffers);
                         }
                         continue;
                 }
-
-                buf->bytesused = bytesused;
-                /* Sync the buffer before we release the qlock */
-                cx18_buf_sync_for_cpu(s, buf);
-                if (s->type == CX18_ENC_STREAM_TYPE_TS) {
-                        /*
-                         * TS doesn't use q_full.  As we pull the buffer off of
-                         * the queue here, the caller will have to put it back.
-                         */
-                        list_del_init(&buf->list);
-                } else {
-                        /* Move buffer from q_busy to q_full */
-                        list_move_tail(&buf->list, &s->q_full.list);
-                        set_bit(CX18_F_B_NEED_BUF_SWAP, &buf->b_flags);
-                        s->q_full.bytesused += buf->bytesused;
-                        atomic_inc(&s->q_full.buffers);
-                }
+                /*
+                 * We pull the desired buffer off of the queue here.  Something
+                 * will have to put it back on a queue later.
+                 */
+                list_del_init(&buf->list);
                 atomic_dec(&s->q_busy.buffers);
-
                 ret = buf;
                 break;
         }
-        mutex_unlock(&s->qlock);
+        spin_unlock(&s->q_busy.lock);
+
+        /*
+         * We found the buffer for which we were looking.  Get it ready for
+         * the caller to put on q_full or in the dvb ring buffer.
+         */
+        if (ret != NULL) {
+                ret->bytesused = bytesused;
+                ret->skipped = 0;
+                /* readpos and b_flags were 0'ed when the buf went on q_busy */
+                cx18_buf_sync_for_cpu(s, ret);
+                if (s->type != CX18_ENC_STREAM_TYPE_TS)
+                        set_bit(CX18_F_B_NEED_BUF_SWAP, &ret->b_flags);
+        }
+
+        /* Put any buffers the firmware is ignoring back into normal rotation */
+        list_for_each_entry_safe(buf, tmp, &sweep_up, list) {
+                list_del_init(&buf->list);
+                cx18_enqueue(s, buf, &s->q_free);
+        }
         return ret;
 }
 
@@ -148,7 +165,7 @@ static void cx18_queue_flush(struct cx18_stream *s, struct cx18_queue *q)
         if (q == &s->q_free)
                 return;
 
-        mutex_lock(&s->qlock);
+        spin_lock(&q->lock);
         while (!list_empty(&q->list)) {
                 buf = list_first_entry(&q->list, struct cx18_buffer, list);
                 list_move_tail(&buf->list, &s->q_free.list);
@@ -156,7 +173,7 @@ static void cx18_queue_flush(struct cx18_stream *s, struct cx18_queue *q)
                 atomic_inc(&s->q_free.buffers);
         }
         cx18_queue_init(q);
-        mutex_unlock(&s->qlock);
+        spin_unlock(&q->lock);
 }
 
 void cx18_flush_queues(struct cx18_stream *s)