@@ -344,11 +344,6 @@ static int vpbe_start_streaming(struct vb2_queue *vq, unsigned int count)
struct vpbe_device *vpbe_dev = fh->disp_dev->vpbe_dev;
int ret;
- /* If buffer queue is empty, return error */
- if (list_empty(&layer->dma_queue)) {
- v4l2_err(&vpbe_dev->v4l2_dev, "buffer queue is empty\n");
- return -ENOBUFS;
- }
/* Get the next frame from the buffer queue */
layer->next_frm = layer->cur_frm = list_entry(layer->dma_queue.next,
struct vpbe_disp_buffer, list);
@@ -1416,6 +1411,7 @@ static int vpbe_display_reqbufs(struct file *file, void *priv,
q->mem_ops = &vb2_dma_contig_memops;
q->buf_struct_size = sizeof(struct vpbe_disp_buffer);
q->timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+ q->min_buffers_needed = 1;
ret = vb2_queue_init(q);
if (ret) {
@@ -272,13 +272,7 @@ static int vpif_start_streaming(struct vb2_queue *vq, unsigned int count)
unsigned long flags;
int ret;
- /* If buffer queue is empty, return error */
spin_lock_irqsave(&common->irqlock, flags);
- if (list_empty(&common->dma_queue)) {
- spin_unlock_irqrestore(&common->irqlock, flags);
- vpif_dbg(1, debug, "buffer queue is empty\n");
- return -ENOBUFS;
- }
/* Get the next frame from the buffer queue */
common->cur_frm = common->next_frm = list_entry(common->dma_queue.next,
@@ -1024,6 +1018,7 @@ static int vpif_reqbufs(struct file *file, void *priv,
q->mem_ops = &vb2_dma_contig_memops;
q->buf_struct_size = sizeof(struct vpif_cap_buffer);
q->timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+ q->min_buffers_needed = 1;
ret = vb2_queue_init(q);
if (ret) {
@@ -234,13 +234,7 @@ static int vpif_start_streaming(struct vb2_queue *vq, unsigned int count)
unsigned long flags;
int ret;
- /* If buffer queue is empty, return error */
spin_lock_irqsave(&common->irqlock, flags);
- if (list_empty(&common->dma_queue)) {
- spin_unlock_irqrestore(&common->irqlock, flags);
- vpif_err("buffer queue is empty\n");
- return -ENOBUFS;
- }
/* Get the next frame from the buffer queue */
common->next_frm = common->cur_frm =
@@ -984,6 +978,7 @@ static int vpif_reqbufs(struct file *file, void *priv,
q->mem_ops = &vb2_dma_contig_memops;
q->buf_struct_size = sizeof(struct vpif_disp_buffer);
q->timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+ q->min_buffers_needed = 1;
ret = vb2_queue_init(q);
if (ret) {
@@ -946,11 +946,6 @@ static int start_streaming(struct vb2_queue *vq, unsigned int count)
mxr_dbg(mdev, "%s\n", __func__);
- if (count == 0) {
- mxr_dbg(mdev, "no output buffers queued\n");
- return -ENOBUFS;
- }
-
/* block any changes in output configuration */
mxr_output_get(mdev);
@@ -1124,6 +1119,7 @@ struct mxr_layer *mxr_base_layer_create(struct mxr_device *mdev,
.drv_priv = layer,
.buf_struct_size = sizeof(struct mxr_buffer),
.ops = &mxr_video_qops,
+ .min_buffers_needed = 1,
.mem_ops = &vb2_dma_contig_memops,
};
@@ -1033,13 +1033,20 @@ EXPORT_SYMBOL_GPL(vb2_plane_cookie);
* 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)
{
@@ -1047,11 +1054,17 @@ 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
/*
@@ -1070,12 +1083,14 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
/* 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);
/* Inform any processes that may be waiting for buffers */
- wake_up(&q->done_wq);
+ if (state != VB2_BUF_STATE_QUEUED)
+ wake_up(&q->done_wq);
}
EXPORT_SYMBOL_GPL(vb2_buffer_done);
@@ -1544,34 +1559,49 @@ EXPORT_SYMBOL_GPL(vb2_prepare_buf);
* 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;
}
@@ -1611,19 +1641,26 @@ static int vb2_internal_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
* dequeued in dqbuf.
*/
list_add_tail(&vb->queued_entry, &q->queued_list);
+ q->queued_count++;
vb->state = VB2_BUF_STATE_QUEUED;
/*
* 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 we haven't yet started streaming and if we have the
+ * minimum number of required buffers available, then 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;
@@ -1778,7 +1815,7 @@ int vb2_wait_for_all_buffers(struct vb2_queue *q)
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;
}
@@ -1839,6 +1876,7 @@ static int vb2_internal_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool n
__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);
@@ -1889,18 +1927,23 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
{
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...
@@ -1923,7 +1966,6 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
{
- struct vb2_buffer *vb;
int ret;
if (type != q->type) {
@@ -1937,17 +1979,15 @@ static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
}
/*
- * 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;
@@ -1201,8 +1201,6 @@ static int vpfe_start_streaming(struct vb2_queue *vq, unsigned int count)
unsigned long addr;
int ret;
- if (count == 0)
- return -ENOBUFS;
ret = mutex_lock_interruptible(&video->lock);
if (ret)
goto streamoff;
@@ -1327,6 +1325,7 @@ static int vpfe_reqbufs(struct file *file, void *priv,
q->type = req_buf->type;
q->io_modes = VB2_MMAP | VB2_USERPTR;
q->drv_priv = fh;
+ q->min_buffers_needed = 1;
q->ops = &video_qops;
q->mem_ops = &vb2_dma_contig_memops;
q->buf_struct_size = sizeof(struct vpfe_cap_buffer);
@@ -348,20 +348,24 @@ struct v4l2_fh;
* @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 {
@@ -377,6 +381,7 @@ struct vb2_queue {
unsigned int buf_struct_size;
u32 timestamp_type;
gfp_t gfp_flags;
+ u32 min_buffers_needed;
/* private: internal use only */
enum v4l2_memory memory;
@@ -384,6 +389,7 @@ struct vb2_queue {
unsigned int num_buffers;
struct list_head queued_list;
+ unsigned int queued_count;
atomic_t owned_by_drv_count;
struct list_head done_list;
@@ -394,7 +400,7 @@ struct vb2_queue {
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;