Hi Andy,
As I mentioned in irc I have been working in this same area as well, so
I'll take this patch and merge it in my tree and test it as well.
I suspect that it might be easiest if I add the patch to my upcoming
patch series in order to prevent merge conflicts. I'll know more later
today.
Regards,
Hans
On 11/21/2013 02:05 AM, Andy Walls wrote:
> (This patch is RFC, because it was compiled and tested against kernel
> v3.5)
>
> videobuf2 file I/O emulation assumed that buffers dequeued from the
> driver would return in the order they were enqueued in the driver.
>
> Improve the file I/O emulator's book-keeping to remove this assumption.
>
> Also remove the, AFAICT, assumption that only read() calls would need to
> dequeue a buffer from the driver.
>
> Also set the buf->size properly, if a write() dequeues a buffer.
>
>
> Signed-off-by: Andy Walls <awalls@xxxxxxxxxxxxxxxx>
> Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Cc: PawelOsciak<pawel@xxxxxxxxxx>
> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
>
>
> diff --git a/drivers/media/video/videobuf2-core.c b/drivers/media/video/videobuf2-core.c
> index 9d4e9ed..f330aa4 100644
> --- a/drivers/media/video/videobuf2-core.c
> +++ b/drivers/media/video/videobuf2-core.c
> @@ -1796,6 +1796,7 @@ struct vb2_fileio_data {
> unsigned int dq_count;
> unsigned int flags;
> };
> +#define FILEIO_INDEX_NOT_SET ((unsigned int) INT_MAX)
>
> /**
> * __vb2_init_fileio() - initialize file io emulator
> @@ -1889,6 +1890,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
> goto err_reqbufs;
> fileio->bufs[i].queued = 1;
> }
> + fileio->index = FILEIO_INDEX_NOT_SET;
>
> /*
> * Start streaming.
> @@ -1975,15 +1977,11 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
> */
> q->fileio = NULL;
>
> - index = fileio->index;
> - buf = &fileio->bufs[index];
> -
> /*
> * Check if we need to dequeue the buffer.
> */
> - if (buf->queued) {
> - struct vb2_buffer *vb;
> -
> + index = fileio->index;
> + if (index == FILEIO_INDEX_NOT_SET) {
> /*
> * Call vb2_dqbuf to get buffer back.
> */
> @@ -1997,12 +1995,19 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
> goto end;
> fileio->dq_count += 1;
>
> + fileio->index = fileio->b.index;
> + index = fileio->index;
> + buf = &fileio->bufs[index];
> +
> /*
> * Get number of bytes filled by the driver
> */
> - vb = q->bufs[index];
> - buf->size = vb2_get_plane_payload(vb, 0);
> + buf->pos = 0;
> buf->queued = 0;
> + buf->size = read ? vb2_get_plane_payload(q->bufs[index], 0)
> + : vb2_plane_size(q->bufs[index], 0);
> + } else {
> + buf = &fileio->bufs[index];
> }
>
> /*
> @@ -2070,13 +2075,28 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
> */
> buf->pos = 0;
> buf->queued = 1;
> - buf->size = q->bufs[0]->v4l2_planes[0].length;
> + buf->size = vb2_plane_size(q->bufs[index], 0);
> fileio->q_count += 1;
>
> /*
> - * Switch to the next buffer
> + * Decide on the next buffer
> */
> - fileio->index = (index + 1) % q->num_buffers;
> + if (read || (q->num_buffers == 1)) {
> + /* Use the next buffer the driver provides back */
> + fileio->index = FILEIO_INDEX_NOT_SET;
> + } else {
> + /* Prefer a buffer that is not quequed in the driver */
> + int initial_index = fileio->index;
> + fileio->index = FILEIO_INDEX_NOT_SET;
> + do {
> + if (++index == q->num_buffers)
> + index = 0;
> + if (!fileio->bufs[index].queued) {
> + fileio->index = index;
> + break;
> + }
> + } while (index != initial_index);
> + }
>
> /*
> * Start streaming if required.
>
>
--
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