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 | 39 +++++++++++++++++++++++++-----
include/media/videobuf2-core.h | 2 ++
2 files changed, 35 insertions(+), 6 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 5cd60bf..33a5d93 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1247,6 +1247,16 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
{
unsigned int plane;
+ if (V4L2_TYPE_IS_OUTPUT(b->type)) {
+ if (WARN_ON_ONCE(b->bytesused == 0)) {
+ pr_warn_once("use of bytesused == 0 is deprecated and will be removed in the future,\n");
+ if (vb->vb2_queue->allow_zero_bytesused)
+ pr_warn_once("use VIDIOC_DECODER_CMD(V4L2_DEC_CMD_STOP) instead.\n");
+ else
+ pr_warn_once("use the actual size instead.\n");
+ }
+ }
+
if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
if (b->memory == V4L2_MEMORY_USERPTR) {
for (plane = 0; plane < vb->num_planes; ++plane) {
@@ -1276,13 +1286,22 @@ 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 +1314,11 @@ 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 +1330,13 @@ 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 e49dc6b..a5790fd 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -337,6 +337,7 @@ struct v4l2_fh;
* @io_modes: supported io methods (see vb2_io_modes enum)
* @fileio_read_once: report EOF after reading the first buffer
* @fileio_write_immediately: queue buffer after each write() call
+ * @allow_zero_bytesused: allow bytesused == 0 to be passed to the driver
* @lock: pointer to a mutex that protects the vb2_queue struct. The
* driver can set this to a mutex to let the v4l2 core serialize
* the queuing ioctls. If the driver wants to handle locking
@@ -388,6 +389,7 @@ 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
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
