Hi Laurent,
There are some typos and the patch is against an old kernel. I'll wait
with an Ack until I see the v2.
Regards,
Hans
On 06/04/14 16:05, Laurent Pinchart wrote:
> When a fatal error occurs that render the device unusable, the only
> options for a driver to signal the error condition to userspace is to
> set the V4L2_BUF_FLAG_ERROR flag when dequeuing buffers and to return an
> error from the buffer prepare handler when queuing buffers.
>
> The buffer error flag indicates a transient error and can't be used by
> applications to detect fatal errors. Returning an error from vb2_qbuf()
> is thus the only real indication that a fatal error occured. However,
> this is difficult to handle for multithreaded applications that requeue
> buffers from a thread other than the control thread. In particular the
> poll() call in the control thread will not notify userspace of the
> error.
>
> This patch adds an explicit mechanism to report fatal errors to
> userspace. Applications can call the vb2_queue_error() function to
^^^^^^^^^^^^ That should be 'Drivers'.
> signal a fatal error. From this moment on, buffer preparation will
> return -EIO to userspace, and vb2_poll() will set the POLLERR flag and
> return immediately. The error flag is cleared when cancelling the queue,
> either at stream off time (through vb2_streamoff) or when releasing the
> queue with vb2_queue_release().
>
> Signed-off-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
> ---
> drivers/media/video/videobuf2-core.c | 41
> +++++++++++++++++++++++++++++++++---
media/video? This patch and the previous one are against some old kernel.
> include/media/videobuf2-core.h | 3 +++
> 2 files changed, 41 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/video/videobuf2-core.c
> b/drivers/media/video/videobuf2-core.c
> index 5f38774..76e3456 100644
> --- a/drivers/media/video/videobuf2-core.c
> +++ b/drivers/media/video/videobuf2-core.c
> @@ -1295,6 +1295,12 @@ int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer
> *b)
> call_qop(q, wait_finish, q);
> }
>
> + if (q->error) {
> + dprintk(1, "qbuf: fatal error occured on queue\n");
typo: 'occurred'
> + ret = -EIO;
> + goto unlock;
> + }
> +
> if (q->fileio) {
> dprintk(1, "qbuf: file io in progress\n");
> ret = -EBUSY;
> @@ -1393,6 +1399,11 @@ static int __vb2_wait_for_done_vb(struct vb2_queue *q,
> int nonblocking)
> return -EINVAL;
> }
>
> + if (q->error) {
> + dprintk(1, "Queue in error state, will not wait for
> buffers\n");
> + return -EIO;
> + }
> +
> if (!list_empty(&q->done_list)) {
> /*
> * Found a buffer that we were waiting for.
> @@ -1418,7 +1429,8 @@ static int __vb2_wait_for_done_vb(struct vb2_queue *q,
> int nonblocking)
> */
> dprintk(3, "Will sleep waiting for buffers\n");
> ret = wait_event_interruptible(q->done_wq,
> - !list_empty(&q->done_list) || !q->streaming);
> + !list_empty(&q->done_list) || !q->streaming ||
> + q->error);
>
> /*
> * We need to reevaluate both conditions again after reacquiring
> @@ -1602,6 +1614,7 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
> if (q->streaming)
> call_qop(q, stop_streaming, q);
> q->streaming = 0;
> + q->error = 0;
>
> /*
> * Remove all buffers from videobuf's list...
> @@ -1623,6 +1636,27 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
> }
>
> /**
> + * vb2_queue_error() - signal a fatal error on the queue
> + * @q: videobuf2 queue
> + *
> + * Flag that a fatal unrecoverable error occured and wake up all processes
> + * waiting on the queue. Polling will now set POLLERR and queuing and
> dequeuing
> + * buffers will return -EIO.
> + *
> + * The error flag will be cleared when cancelling the queue, either from
> + * vb2_streamoff or vb2_queue_release. Drivers should thus not call this
> + * function before starting the stream, otherwise the error flag will remain
> set
> + * until the queue is released when closing the device node.
> + */
> +void vb2_queue_error(struct vb2_queue *q)
> +{
> + q->error = 1;
> +
> + wake_up_all(&q->done_wq);
> +}
> +EXPORT_SYMBOL_GPL(vb2_queue_error);
> +
> +/**
> * vb2_streamon - start streaming
> * @q: videobuf2 queue
> * @type: type argument passed from userspace to vidioc_streamon handler
> @@ -1984,9 +2018,10 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file
> *file, poll_table *wait)
> }
>
> /*
> - * There is nothing to wait for if the queue isn't streaming.
> + * There is nothing to wait for if the queue isn't streaming or if the
> + * error flag is set.
> */
> - if (!vb2_is_streaming(q))
> + if (!vb2_is_streaming(q) || q->error)
> return res | POLLERR;
>
> poll_wait(file, &q->done_wq, wait);
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index d173206..352e6ca 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -302,6 +302,7 @@ struct vb2_ops {
> * @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
> + * @error: a fatal error occured on the queue
'occurred'
> * @fileio: file io emulator internal data, used only if emulator is active
> */
> struct vb2_queue {
> @@ -330,6 +331,7 @@ struct vb2_queue {
> unsigned int plane_sizes[VIDEO_MAX_PLANES];
>
> unsigned int streaming:1;
> + unsigned int error:1;
>
> struct vb2_fileio_data *fileio;
> };
> @@ -349,6 +351,7 @@ int vb2_prepare_buf(struct vb2_queue *q, struct
> v4l2_buffer *b);
> int __must_check vb2_queue_init(struct vb2_queue *q);
>
> void vb2_queue_release(struct vb2_queue *q);
> +void vb2_queue_error(struct vb2_queue *q);
>
> int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
> int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb);
>
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