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

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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>
This commit is contained in:
Andy Walls 2009-04-13 23:08:00 -03:00 committed by Mauro Carvalho Chehab
parent 5f0a3cfcfd
commit 40c5520f55
4 changed files with 68 additions and 48 deletions
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2
drivers/media/video/cx18/cx18-driver.h
View file

@ -286,6 +286,7 @@ struct cx18_queue {
struct list_head list;
atomic_t buffers;
u32 bytesused;
spinlock_t lock;
};
struct cx18_dvb {
@ -365,7 +366,6 @@ struct cx18_stream {
unsigned mdl_offset;
u32 id;
struct mutex qlock; /* locks access to the queues */
unsigned long s_flags; /* status flags, see above */
int dma; /* can be PCI_DMA_TODEVICE,
PCI_DMA_FROMDEVICE or

25
drivers/media/video/cx18/cx18-mailbox.c
View file

@ -191,23 +191,24 @@ static void epu_dma_done(struct cx18 *cx, struct cx18_in_work_order *order)
if (buf == NULL) {
CX18_WARN("Could not find buf %d for stream %s\n",
id, s->name);
/* Put as many buffers as possible back into fw use */
cx18_stream_load_fw_queue(s);
continue;
}
if (s->type == CX18_ENC_STREAM_TYPE_TS && s->dvb.enabled) {
CX18_DEBUG_HI_DMA("TS recv bytesused = %d\n",
buf->bytesused);
dvb_dmx_swfilter(&s->dvb.demux, buf->buf,
buf->bytesused);
CX18_DEBUG_HI_DMA("%s recv bytesused = %d\n",
s->name, buf->bytesused);
if (s->type != CX18_ENC_STREAM_TYPE_TS)
cx18_enqueue(s, buf, &s->q_full);
else {
if (s->dvb.enabled)
dvb_dmx_swfilter(&s->dvb.demux, buf->buf,
buf->bytesused);
cx18_enqueue(s, buf, &s->q_free);
}
/* Put as many buffers as possible back into fw use */
cx18_stream_load_fw_queue(s);
/* Put back TS buffer, since it was removed from all queues */
if (s->type == CX18_ENC_STREAM_TYPE_TS)
cx18_stream_put_buf_fw(s, buf);
}
/* Put as many buffers as possible back into fw use */
cx18_stream_load_fw_queue(s);
wake_up(&cx->dma_waitq);
if (s->id != -1)
wake_up(&s->waitq);

81
drivers/media/video/cx18/cx18-queue.c
View file

@ -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;
LIST_HEAD(sweep_up);
mutex_lock(&s->qlock);
/*
* 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)

8
drivers/media/video/cx18/cx18-streams.c
View file

@ -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 */