* Make sure the requested values and current defaults are sane.
*/
num_buffers = min_t(unsigned int, req->count, VIDEO_MAX_FRAME);
+ num_buffers = max_t(unsigned int, req->count, q->min_buffers_needed);
memset(q->plane_sizes, 0, sizeof(q->plane_sizes));
memset(q->alloc_ctx, 0, sizeof(q->alloc_ctx));
q->memory = req->memory;
return -ENOMEM;
}
+ /*
+ * There is no point in continuing if we can't allocate the minimum
+ * number of buffers needed by this vb2_queue.
+ */
+ if (allocated_buffers < q->min_buffers_needed)
+ ret = -ENOMEM;
+
/*
* Check if driver can handle the allocated number of buffers.
*/
- if (allocated_buffers < num_buffers) {
+ if (!ret && allocated_buffers < num_buffers) {
num_buffers = allocated_buffers;
ret = call_qop(q, queue_setup, q, NULL, &num_buffers,
* vb2_buffer_done() - inform videobuf that an operation on a buffer is finished
* @vb: vb2_buffer returned from the driver
* @state: either VB2_BUF_STATE_DONE if the operation finished successfully
- * or VB2_BUF_STATE_ERROR if the operation finished with an error
+ * or VB2_BUF_STATE_ERROR if the operation finished with an error.
+ * If start_streaming fails then it should return buffers with state
+ * VB2_BUF_STATE_QUEUED to put them back into the queue.
*
* This function should be called by the driver after a hardware operation on
* a buffer is finished and the buffer may be returned to userspace. The driver
* cannot use this buffer anymore until it is queued back to it by videobuf
* by the means of buf_queue callback. Only buffers previously queued to the
* driver by buf_queue can be passed to this function.
+ *
+ * While streaming a buffer can only be returned in state DONE or ERROR.
+ * The start_streaming op can also return them in case the DMA engine cannot
+ * be started for some reason. In that case the buffers should be returned with
+ * state QUEUED.
*/
void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
{
unsigned long flags;
unsigned int plane;
- if (vb->state != VB2_BUF_STATE_ACTIVE)
+ if (WARN_ON(vb->state != VB2_BUF_STATE_ACTIVE))
return;
- if (state != VB2_BUF_STATE_DONE && state != VB2_BUF_STATE_ERROR)
- return;
+ if (!q->start_streaming_called) {
+ if (WARN_ON(state != VB2_BUF_STATE_QUEUED))
+ state = VB2_BUF_STATE_QUEUED;
+ } else if (!WARN_ON(!q->start_streaming_called)) {
+ if (WARN_ON(state != VB2_BUF_STATE_DONE &&
+ state != VB2_BUF_STATE_ERROR))
+ state = VB2_BUF_STATE_ERROR;
+ }
#ifdef CONFIG_VIDEO_ADV_DEBUG
/*
/* Add the buffer to the done buffers list */
spin_lock_irqsave(&q->done_lock, flags);
vb->state = state;
- list_add_tail(&vb->done_entry, &q->done_list);
+ if (state != VB2_BUF_STATE_QUEUED)
+ list_add_tail(&vb->done_entry, &q->done_list);
atomic_dec(&q->owned_by_drv_count);
spin_unlock_irqrestore(&q->done_lock, flags);
+ if (state == VB2_BUF_STATE_QUEUED)
+ return;
+
/* Inform any processes that may be waiting for buffers */
wake_up(&q->done_wq);
}
* vb2_start_streaming() - Attempt to start streaming.
* @q: videobuf2 queue
*
- * If there are not enough buffers, then retry_start_streaming is set to
- * 1 and 0 is returned. The next time a buffer is queued and
- * retry_start_streaming is 1, this function will be called again to
- * retry starting the DMA engine.
+ * Attempt to start streaming. When this function is called there must be
+ * at least q->min_buffers_needed buffers queued up (i.e. the minimum
+ * number of buffers required for the DMA engine to function). If the
+ * @start_streaming op fails it is supposed to return all the driver-owned
+ * buffers back to vb2 in state QUEUED. Check if that happened and if
+ * not warn and reclaim them forcefully.
*/
static int vb2_start_streaming(struct vb2_queue *q)
{
+ struct vb2_buffer *vb;
int ret;
- /* Tell the driver to start streaming */
- ret = call_qop(q, start_streaming, q, atomic_read(&q->owned_by_drv_count));
- if (ret)
- fail_qop(q, start_streaming);
-
/*
- * If there are not enough buffers queued to start streaming, then
- * the start_streaming operation will return -ENOBUFS and you have to
- * retry when the next buffer is queued.
+ * If any buffers were queued before streamon,
+ * we can now pass them to driver for processing.
*/
- if (ret == -ENOBUFS) {
- dprintk(1, "qbuf: not enough buffers, retry when more buffers are queued.\n");
- q->retry_start_streaming = 1;
+ list_for_each_entry(vb, &q->queued_list, queued_entry)
+ __enqueue_in_driver(vb);
+
+ /* Tell the driver to start streaming */
+ ret = call_qop(q, start_streaming, q,
+ atomic_read(&q->owned_by_drv_count));
+ q->start_streaming_called = ret == 0;
+ if (!ret)
return 0;
+
+ fail_qop(q, start_streaming);
+ dprintk(1, "qbuf: driver refused to start streaming\n");
+ if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
+ unsigned i;
+
+ /*
+ * Forcefully reclaim buffers if the driver did not
+ * correctly return them to vb2.
+ */
+ for (i = 0; i < q->num_buffers; ++i) {
+ vb = q->bufs[i];
+ if (vb->state == VB2_BUF_STATE_ACTIVE)
+ vb2_buffer_done(vb, VB2_BUF_STATE_QUEUED);
+ }
+ /* Must be zero now */
+ WARN_ON(atomic_read(&q->owned_by_drv_count));
}
- if (ret)
- dprintk(1, "qbuf: driver refused to start streaming\n");
- else
- q->retry_start_streaming = 0;
return ret;
}
* dequeued in dqbuf.
*/
list_add_tail(&vb->queued_entry, &q->queued_list);
+ q->queued_count++;
vb->state = VB2_BUF_STATE_QUEUED;
if (V4L2_TYPE_IS_OUTPUT(q->type)) {
/*
* If already streaming, give the buffer to driver for processing.
* If not, the buffer will be given to driver on next streamon.
*/
- if (q->streaming)
+ if (q->start_streaming_called)
__enqueue_in_driver(vb);
/* Fill buffer information for the userspace */
__fill_v4l2_buffer(vb, b);
- if (q->retry_start_streaming) {
+ /*
+ * If streamon has been called, and we haven't yet called
+ * start_streaming() since not enough buffers were queued, and
+ * we now have reached the minimum number of queued buffers,
+ * then we can finally call start_streaming().
+ */
+ if (q->streaming && !q->start_streaming_called &&
+ q->queued_count >= q->min_buffers_needed) {
ret = vb2_start_streaming(q);
if (ret)
return ret;
return -EINVAL;
}
- if (!q->retry_start_streaming)
+ if (q->start_streaming_called)
wait_event(q->done_wq, !atomic_read(&q->owned_by_drv_count));
return 0;
}
__fill_v4l2_buffer(vb, b);
/* Remove from videobuf queue */
list_del(&vb->queued_entry);
+ q->queued_count--;
/* go back to dequeued state */
__vb2_dqbuf(vb);
{
unsigned int i;
- if (q->retry_start_streaming) {
- q->retry_start_streaming = 0;
- q->streaming = 0;
- }
-
/*
* Tell driver to stop all transactions and release all queued
* buffers.
*/
- if (q->streaming)
+ if (q->start_streaming_called)
call_qop(q, stop_streaming, q);
q->streaming = 0;
+ q->start_streaming_called = 0;
+ q->queued_count = 0;
+
+ if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
+ for (i = 0; i < q->num_buffers; ++i)
+ if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
+ vb2_buffer_done(q->bufs[i], VB2_BUF_STATE_ERROR);
+ /* Must be zero now */
+ WARN_ON(atomic_read(&q->owned_by_drv_count));
+ }
/*
* Remove all buffers from videobuf's list...
static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
{
- struct vb2_buffer *vb;
int ret;
if (type != q->type) {
dprintk(1, "streamon: no buffers have been allocated\n");
return -EINVAL;
}
+ if (q->num_buffers < q->min_buffers_needed) {
+ dprintk(1, "streamon: need at least %u allocated buffers\n",
+ q->min_buffers_needed);
+ return -EINVAL;
+ }
/*
- * If any buffers were queued before streamon,
- * we can now pass them to driver for processing.
+ * Tell driver to start streaming provided sufficient buffers
+ * are available.
*/
- list_for_each_entry(vb, &q->queued_list, queued_entry)
- __enqueue_in_driver(vb);
-
- /* Tell driver to start streaming. */
- ret = vb2_start_streaming(q);
- if (ret) {
- __vb2_queue_cancel(q);
- return ret;
+ if (q->queued_count >= q->min_buffers_needed) {
+ ret = vb2_start_streaming(q);
+ if (ret) {
+ __vb2_queue_cancel(q);
+ return ret;
+ }
}
q->streaming = 1;
* @gfp_flags: additional gfp flags used when allocating the buffers.
* Typically this is 0, but it may be e.g. GFP_DMA or __GFP_DMA32
* to force the buffer allocation to a specific memory zone.
+ * @min_buffers_needed: the minimum number of buffers needed before
+ * start_streaming() can be called. Used when a DMA engine
+ * cannot be started unless at least this number of buffers
+ * have been queued into the driver.
*
* @memory: current memory type used
* @bufs: videobuf buffer structures
* @num_buffers: number of allocated/used buffers
* @queued_list: list of buffers currently queued from userspace
+ * @queued_count: number of buffers queued and ready for streaming.
* @owned_by_drv_count: number of buffers owned by the driver
* @done_list: list of buffers ready to be dequeued to userspace
* @done_lock: lock to protect done_list list
* @done_wq: waitqueue for processes waiting for buffers ready to be dequeued
* @alloc_ctx: memory type/allocator-specific contexts for each plane
* @streaming: current streaming state
- * @retry_start_streaming: start_streaming() was called, but there were not enough
- * buffers queued. If set, then retry calling start_streaming when
- * queuing a new buffer.
+ * @start_streaming_called: start_streaming() was called successfully and we
+ * started streaming.
* @fileio: file io emulator internal data, used only if emulator is active
*/
struct vb2_queue {
unsigned int buf_struct_size;
u32 timestamp_flags;
gfp_t gfp_flags;
+ u32 min_buffers_needed;
/* private: internal use only */
enum v4l2_memory memory;
unsigned int num_buffers;
struct list_head queued_list;
+ unsigned int queued_count;
atomic_t owned_by_drv_count;
struct list_head done_list;
unsigned int plane_sizes[VIDEO_MAX_PLANES];
unsigned int streaming:1;
- unsigned int retry_start_streaming:1;
+ unsigned int start_streaming_called:1;
struct vb2_fileio_data *fileio;
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