From 4898ebd32abf45917d84356171f9b18e52d58697 Mon Sep 17 00:00:00 2001 From: Andy Walls Date: Mon, 13 Apr 2009 22:08:00 -0400 Subject: cx18: Convert per stream mutex locks to per queue spin locks From: Andy Walls 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. Priority: normal Signed-off-by: Andy Walls --- linux/drivers/media/video/cx18/cx18-queue.c | 83 +++++++++++++++++------------ 1 file changed, 50 insertions(+), 33 deletions(-) (limited to 'linux/drivers/media/video/cx18/cx18-queue.c') diff --git a/linux/drivers/media/video/cx18/cx18-queue.c b/linux/drivers/media/video/cx18/cx18-queue.c index 3046b8e74..693a745b0 100644 --- a/linux/drivers/media/video/cx18/cx18-queue.c +++ b/linux/drivers/media/video/cx18/cx18-queue.c @@ -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) -- cgit v1.2.3 From aa8de0afdd1a794bcd8f80c83ca7710c0050894a Mon Sep 17 00:00:00 2001 From: Andy Walls Date: Wed, 15 Apr 2009 19:45:10 -0400 Subject: cx18: Simplify the work handler for outgoing mailbox commands From: Andy Walls Simplify the way outgoing work handler gets scheduled to send empty buffers back to the firmware for use. Also reduced the memory required for scheduling this outgoing work, by using a single, per stream work object. Priority: normal Signed-off-by: Andy Walls --- linux/drivers/media/video/cx18/cx18-queue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'linux/drivers/media/video/cx18/cx18-queue.c') diff --git a/linux/drivers/media/video/cx18/cx18-queue.c b/linux/drivers/media/video/cx18/cx18-queue.c index 693a745b0..fa1ed7897 100644 --- a/linux/drivers/media/video/cx18/cx18-queue.c +++ b/linux/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) -- cgit v1.2.3