(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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