On 02/18/2015 06:07 PM, Kamil Debski wrote:
> 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.
Can you do this in two patches? One that changes io_flags to a bitfield,
and one adding the new flag.
See more remarks in videobuf2-core.h below.
>
> Reported-by: Nicolas Dufresne <nicolas.dufre...@collabora.com>
> Signed-off-by: Kamil Debski <k.deb...@samsung.com>
> ---
> 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)
io_flags no longer exists.
> + * XXX
???
I assume you intended to move the enum vb2_fileio_flags comments here.
> * @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;
>
>
Regards,
Hans
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