The vb2: fix bytesused == 0 handling (8a75ffb) patch changed the behavior
of __fill_vb2_buffer function, so that if bytesused is 0 it is set to the
size of the buffer. However, bytesused set to 0 is used by older codec
drivers as as indication used to mark the end of stream.
To keep backward compatibility, this patch adds a flag passed to the
vb2_queue_init function - allow_zero_bytesused. If the flag is set upon
initialization of the queue, the videobuf2 keeps the value of bytesused
intact in the OUTPUT queue and passes it to the driver.
Reported-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
Signed-off-by: Kamil Debski <k.debski@xxxxxxxxxxx>
---
drivers/media/v4l2-core/videobuf2-core.c | 29 +++++++++++++++++++++++------
include/media/videobuf2-core.h | 1 +
2 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 62531956..487e31f 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1276,13 +1276,22 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
* userspace clearly never bothered to set it and
* it's a safe assumption that they really meant to
* use the full plane sizes.
+ *
+ * Some drivers, e.g. old codec drivers, use bytesused
+ * == 0 as a way to indicate that streaming is finished.
+ * In that case, the driver should use the
+ * allow_zero_bytesused flag to keep old userspace
+ * applications working.
*/
for (plane = 0; plane < vb->num_planes; ++plane) {
struct v4l2_plane *pdst = &v4l2_planes[plane];
struct v4l2_plane *psrc = &b->m.planes[plane];
- pdst->bytesused = psrc->bytesused ?
- psrc->bytesused : pdst->length;
+ if (vb->vb2_queue->allow_zero_bytesused)
+ pdst->bytesused = psrc->bytesused;
+ else
+ pdst->bytesused = psrc->bytesused ?
+ psrc->bytesused : pdst->length;
pdst->data_offset = psrc->data_offset;
}
}
@@ -1295,6 +1304,11 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
*
* If bytesused == 0 for the output buffer, then fall back
* to the full buffer size as that's a sensible default.
+ *
+ * Some drivers, e.g. old codec drivers, use bytesused * == 0 as
+ * a way to indicate that streaming is finished. In that case,
+ * the driver should use the allow_zero_bytesused flag to keep
+ * old userspace applications working.
*/
if (b->memory == V4L2_MEMORY_USERPTR) {
v4l2_planes[0].m.userptr = b->m.userptr;
@@ -1306,10 +1320,13 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
v4l2_planes[0].length = b->length;
}
- if (V4L2_TYPE_IS_OUTPUT(b->type))
- v4l2_planes[0].bytesused = b->bytesused ?
- b->bytesused : v4l2_planes[0].length;
- else
+ if (V4L2_TYPE_IS_OUTPUT(b->type)) {
+ if (vb->vb2_queue->allow_zero_bytesused)
+ v4l2_planes[0].bytesused = b->bytesused;
+ else
+ v4l2_planes[0].bytesused = b->bytesused ?
+ b->bytesused : v4l2_planes[0].length;
+ } else
v4l2_planes[0].bytesused = 0;
}
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 1346693..50111bd573 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -388,6 +388,7 @@ struct vb2_queue {
unsigned int io_modes;
unsigned fileio_read_once:1;
unsigned fileio_write_immediately:1;
+ unsigned allow_zero_bytesused:1;
struct mutex *lock;
struct v4l2_fh *owner;
--
1.7.9.5
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