Drivers can now finish processing on and return video buffers in
an arbitrary order. Before this patch, this was possible in a FIFO order
only. This is useful e.g. for video codecs, which often need to hold some
buffers (e.g. keyframes) for longer periods of time than others.
Signed-off-by: Pawel Osciak <p.osciak@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
drivers/media/video/videobuf-core.c | 160 +++++++++++++++++++++++-----------
include/media/videobuf-core.h | 9 ++
2 files changed, 117 insertions(+), 52 deletions(-)
diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c
index 77899ca..ea5fd39 100644
--- a/drivers/media/video/videobuf-core.c
+++ b/drivers/media/video/videobuf-core.c
@@ -95,6 +95,27 @@ int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr)
}
EXPORT_SYMBOL_GPL(videobuf_waiton);
+int videobuf_has_consumers(struct videobuf_queue *q)
+{
+ return waitqueue_active(&q->vb_done_wait);
+}
+EXPORT_SYMBOL_GPL(videobuf_has_consumers);
+
+void videobuf_buf_finish(struct videobuf_queue *q, struct videobuf_buffer *vb)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&q->vb_done_lock, flags);
+ list_add_tail(&vb->done_list, &q->vb_done_list);
+ spin_unlock_irqrestore(&q->vb_done_lock, flags);
+
+ spin_lock_irqsave(q->irqlock, flags);
+ wake_up(&vb->done);
+ wake_up_interruptible(&q->vb_done_wait);
+ spin_unlock_irqrestore(q->irqlock, flags);
+}
+EXPORT_SYMBOL_GPL(videobuf_buf_finish);
+
int videobuf_iolock(struct videobuf_queue *q, struct videobuf_buffer *vb,
struct v4l2_framebuffer *fbuf)
{
@@ -153,7 +174,10 @@ void videobuf_queue_core_init(struct videobuf_queue *q,
mutex_init(&q->vb_lock);
init_waitqueue_head(&q->wait);
+ init_waitqueue_head(&q->vb_done_wait);
INIT_LIST_HEAD(&q->stream);
+ INIT_LIST_HEAD(&q->vb_done_list);
+ spin_lock_init(&q->vb_done_lock);
}
EXPORT_SYMBOL_GPL(videobuf_queue_core_init);
@@ -217,6 +241,7 @@ void videobuf_queue_cancel(struct videobuf_queue *q)
wake_up_all(&q->bufs[i]->done);
}
}
+ wake_up_all(&q->vb_done_wait);
spin_unlock_irqrestore(q->irqlock, flags);
/* free all buffers + clear queue */
@@ -603,67 +628,81 @@ done:
EXPORT_SYMBOL_GPL(videobuf_qbuf);
/* Locking: Caller holds q->vb_lock */
-static int stream_next_buffer_check_queue(struct videobuf_queue *q, int noblock)
+static int wait_for_buffer(struct videobuf_queue *q, int nonblocking)
{
- int retval;
+ int retval = 0;
checks:
if (!q->streaming) {
- dprintk(1, "next_buffer: Not streaming\n");
+ dprintk(1, "Not streaming\n");
retval = -EINVAL;
- goto done;
+ goto end;
}
- if (list_empty(&q->stream)) {
- if (noblock) {
+ /*
+ * Buffers may be added to vb_done_list without holding the vb_lock,
+ * but removal is performed only while holding both vb_lock and the
+ * vb_done_lock spinlock. Thus we can be sure that as long as we hold
+ * vb_lock, the list will remain not empty if this check succeeds.
+ */
+ if (list_empty(&q->vb_done_list)) {
+ if (nonblocking) {
+ dprintk(1, "Nonblocking and no buffers to dequeue\n");
retval = -EAGAIN;
- dprintk(2, "next_buffer: no buffers to dequeue\n");
- goto done;
- } else {
- dprintk(2, "next_buffer: waiting on buffer\n");
-
- /* Drop lock to avoid deadlock with qbuf */
- mutex_unlock(&q->vb_lock);
-
- /* Checking list_empty and streaming is safe without
- * locks because we goto checks to validate while
- * holding locks before proceeding */
- retval = wait_event_interruptible(q->wait,
- !list_empty(&q->stream) || !q->streaming);
- mutex_lock(&q->vb_lock);
-
- if (retval)
- goto done;
-
- goto checks;
+ goto end;
}
- }
- retval = 0;
+ /*
+ * We are streaming and nonblocking, wait for another buffer to
+ * become ready or for streamoff. vb_lock is released to allow
+ * streamoff and qbuf in parallel.
+ */
+ mutex_unlock(&q->vb_lock);
+ /*
+ * Although the mutex is released here, we will be reevaluating
+ * both conditions again after reacquiring it.
+ */
+ retval = wait_event_interruptible(q->vb_done_wait,
+ !list_empty(&q->vb_done_list) || !q->streaming);
+ mutex_lock(&q->vb_lock);
+
+ if (retval)
+ goto end;
+
+ goto checks;
+ }
-done:
+ /*
+ * At least one buffer is on the vb_done_list and nothing can be removed
+ * from it without acquiring the vb_lock, which we are holding now.
+ */
+end:
return retval;
}
/* Locking: Caller holds q->vb_lock */
-static int stream_next_buffer(struct videobuf_queue *q,
- struct videobuf_buffer **vb, int nonblocking)
+static int get_done_buffer(struct videobuf_queue *q,
+ struct videobuf_buffer **vb, int nonblocking)
{
- int retval;
- struct videobuf_buffer *buf = NULL;
-
- retval = stream_next_buffer_check_queue(q, nonblocking);
- if (retval)
- goto done;
-
- buf = list_entry(q->stream.next, struct videobuf_buffer, stream);
- retval = videobuf_waiton(buf, nonblocking, 1);
- if (retval < 0)
- goto done;
-
- *vb = buf;
-done:
- return retval;
+ unsigned long flags;
+ int ret = 0;
+
+ ret = wait_for_buffer(q, nonblocking);
+ if (ret)
+ goto end;
+
+ /*
+ * vb_lock has been held since we last verified that vb_done_list is
+ * not empty, no need for another list_empty().
+ */
+ spin_lock_irqsave(&q->vb_done_lock, flags);
+ *vb = list_first_entry(&q->vb_done_list, struct videobuf_buffer,
+ done_list);
+ list_del(&((*vb)->done_list));
+ spin_unlock_irqrestore(&q->vb_done_lock, flags);
+
+end:
+ return ret;
}
int videobuf_dqbuf(struct videobuf_queue *q,
@@ -676,7 +715,7 @@ int videobuf_dqbuf(struct videobuf_queue *q,
mutex_lock(&q->vb_lock);
- retval = stream_next_buffer(q, &buf, nonblocking);
+ retval = get_done_buffer(q, &buf, nonblocking);
if (retval < 0) {
dprintk(1, "dqbuf: next_buffer error: %i\n", retval);
goto done;
@@ -1055,12 +1094,25 @@ unsigned int videobuf_poll_stream(struct file *file,
{
struct videobuf_buffer *buf = NULL;
unsigned int rc = 0;
+ unsigned long flags;
mutex_lock(&q->vb_lock);
if (q->streaming) {
- if (!list_empty(&q->stream))
- buf = list_entry(q->stream.next,
- struct videobuf_buffer, stream);
+ if (list_empty(&q->stream)) {
+ rc = POLLERR;
+ goto end;
+ }
+
+ poll_wait(file, &q->vb_done_wait, wait);
+
+ spin_lock_irqsave(&q->vb_done_lock, flags);
+ if (!list_empty(&q->vb_done_list))
+ buf = list_first_entry(&q->vb_done_list,
+ struct videobuf_buffer,
+ done_list);
+ spin_unlock_irqrestore(&q->vb_done_lock, flags);
+ if (!buf)
+ goto end;
} else {
if (!q->reading)
__videobuf_read_start(q);
@@ -1074,12 +1126,15 @@ unsigned int videobuf_poll_stream(struct file *file,
q->read_off = 0;
}
buf = q->read_buf;
+ if (!buf) {
+ rc = POLLERR;
+ goto end;
+ }
+
+ poll_wait(file, &buf->done, wait);
}
- if (!buf)
- rc = POLLERR;
if (0 == rc) {
- poll_wait(file, &buf->done, wait);
if (buf->state == VIDEOBUF_DONE ||
buf->state == VIDEOBUF_ERROR) {
switch (q->type) {
@@ -1094,6 +1149,7 @@ unsigned int videobuf_poll_stream(struct file *file,
}
}
}
+end:
mutex_unlock(&q->vb_lock);
return rc;
}
diff --git a/include/media/videobuf-core.h b/include/media/videobuf-core.h
index b1f7bf4..7b1cc94 100644
--- a/include/media/videobuf-core.h
+++ b/include/media/videobuf-core.h
@@ -82,6 +82,7 @@ struct videobuf_buffer {
enum v4l2_field field;
enum videobuf_state state;
struct list_head stream; /* QBUF/DQBUF list */
+ struct list_head done_list;
/* touched by irq handler */
struct list_head queue;
@@ -160,6 +161,10 @@ struct videobuf_queue {
wait_queue_head_t wait; /* wait if queue is empty */
+ wait_queue_head_t vb_done_wait;
+ struct list_head vb_done_list;
+ spinlock_t vb_done_lock;
+
enum v4l2_buf_type type;
unsigned int inputs; /* for V4L2_BUF_FLAG_INPUT */
unsigned int msize;
@@ -206,6 +211,8 @@ void videobuf_queue_core_init(struct videobuf_queue *q,
int videobuf_queue_is_busy(struct videobuf_queue *q);
void videobuf_queue_cancel(struct videobuf_queue *q);
+void videobuf_buf_finish(struct videobuf_queue *q, struct videobuf_buffer *vb);
+
enum v4l2_field videobuf_next_field(struct videobuf_queue *q);
int videobuf_reqbufs(struct videobuf_queue *q,
struct v4l2_requestbuffers *req);
@@ -235,6 +242,8 @@ unsigned int videobuf_poll_stream(struct file *file,
struct videobuf_queue *q,
poll_table *wait);
+int videobuf_has_consumers(struct videobuf_queue *q);
+
int videobuf_mmap_setup(struct videobuf_queue *q,
unsigned int bcount, unsigned int bsize,
enum v4l2_memory memory);
--
1.7.1.rc1.12.ga601
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