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.
This patch splits the io_flags member of vb2_queue into a bit field.
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 | 44 ++++++++++++++++++++++--------
include/media/videobuf2-core.h | 17 ++++--------
2 files changed, 37 insertions(+), 24 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index bc08a82..e7e8ce5 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;
}
@@ -2760,7 +2777,8 @@ struct vb2_fileio_data {
unsigned int initial_index;
unsigned int q_count;
unsigned int dq_count;
- unsigned int flags;
+ unsigned read_once:1;
+ unsigned write_immediately:1;
};
/**
@@ -2798,14 +2816,16 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
*/
count = 1;
- dprintk(3, "setting up file io: mode %s, count %d, flags %08x\n",
- (read) ? "read" : "write", count, q->io_flags);
+ dprintk(3, "setting up file io: mode %s, count %d, read_once %d, write_immediately %d, allow_zero_bytesused %d\n",
+ (read) ? "read" : "write", count, q->fileio_read_once,
+ q->fileio_write_immediately, q->allow_zero_bytesused);
fileio = kzalloc(sizeof(struct vb2_fileio_data), GFP_KERNEL);
if (fileio == NULL)
return -ENOMEM;
- fileio->flags = q->io_flags;
+ fileio->read_once = q->fileio_read_once;
+ fileio->write_immediately = q->fileio_write_immediately;
/*
* Request buffers and use MMAP type to force driver
@@ -3029,11 +3049,11 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
* Queue next buffer if required.
*/
if (buf->pos == buf->size ||
- (!read && (fileio->flags & VB2_FILEIO_WRITE_IMMEDIATELY))) {
+ (!read && (fileio->write_immediately))) {
/*
* Check if this is the last buffer to read.
*/
- if (read && (fileio->flags & VB2_FILEIO_READ_ONCE) &&
+ if (read && (fileio->read_once) &&
fileio->dq_count == 1) {
dprintk(3, "read limit reached\n");
return __vb2_cleanup_fileio(q);
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index bd2cec2..50111bd573 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -134,17 +134,6 @@ enum vb2_io_modes {
};
/**
- * enum vb2_fileio_flags - flags for selecting a mode of the file io emulator,
- * by default the 'streaming' style is used by the file io emulator
- * @VB2_FILEIO_READ_ONCE: report EOF after reading the first buffer
- * @VB2_FILEIO_WRITE_IMMEDIATELY: queue buffer after each write() call
- */
-enum vb2_fileio_flags {
- VB2_FILEIO_READ_ONCE = (1 << 0),
- VB2_FILEIO_WRITE_IMMEDIATELY = (1 << 1),
-};
-
-/**
* enum vb2_buffer_state - current video buffer state
* @VB2_BUF_STATE_DEQUEUED: buffer under userspace control
* @VB2_BUF_STATE_PREPARING: buffer is being prepared in videobuf
@@ -347,6 +336,7 @@ struct v4l2_fh;
* @type: queue type (see V4L2_BUF_TYPE_* in linux/videodev2.h
* @io_modes: supported io methods (see vb2_io_modes enum)
* @io_flags: additional io flags (see vb2_fileio_flags enum)
+ * XXX
* @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
@@ -396,7 +386,10 @@ struct v4l2_fh;
struct vb2_queue {
enum v4l2_buf_type type;
unsigned int io_modes;
- unsigned int io_flags;
+ 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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