On Wednesday, June 29, 2011 11:49:06 Marek Szyprowski wrote:
> This patch introduces VB2_STREAMON_WITHOUT_BUFFERS io flag and changes
> the order of operations during stream on operation. Now the buffer are
> first queued to the driver and then the start_streaming method is called.
> This resolves the most common case when the driver needs to know buffer
> addresses to enable dma engine and start streaming. For drivers that can
> handle start_streaming without queued buffers (mem2mem and 'one shot'
> capture case) a new VB2_STREAMON_WITHOUT_BUFFERS io flag has been
> introduced. Driver can set it to let videobuf2 know that it support this
> mode.
>
> This patch also updates videobuf2 clients (s5p-fimc, mem2mem_testdev and
> vivi) to work properly with the changed order of operations and enables
> use of the newly introduced flag.
>
> Signed-off-by: Marek Szyprowski <[email protected]>
> Signed-off-by: Sylwester Nawrocki <[email protected]>
> Signed-off-by: Kyungmin Park <[email protected]>
> CC: Pawel Osciak <[email protected]>
> ---
>
> drivers/media/video/mem2mem_testdev.c | 4 +-
> drivers/media/video/s5p-fimc/fimc-capture.c | 65
++++++++++++++++----------
> drivers/media/video/s5p-fimc/fimc-core.c | 4 +-
> drivers/media/video/videobuf2-core.c | 21 ++++-----
> drivers/media/video/vivi.c | 2 +-
> include/media/videobuf2-core.h | 11 +++--
> 6 files changed, 62 insertions(+), 45 deletions(-)
>
>
> ---
>
> Hello,
>
> This patch introduces significant changes in the vb2 streamon operation,
> so all vb2 clients need to be checked and updated. Right now I didn't
> update mx3_camera and sh_mobile_ceu_camera drivers. Once we agree that
> this patch can be merged, I will update it to include all the required
> changes to these two drivers as well.
>
> Best regards
> --
> Marek Szyprowski
> Samsung Poland R&D Center
>
<snip>
> diff --git a/drivers/media/video/videobuf2-core.c
b/drivers/media/video/videobuf2-core.c
> index 5517913..911e2eb 100644
> --- a/drivers/media/video/videobuf2-core.c
> +++ b/drivers/media/video/videobuf2-core.c
> @@ -1136,17 +1136,23 @@ int vb2_streamon(struct vb2_queue *q, enum
v4l2_buf_type type)
> }
>
> /*
> - * Cannot start streaming on an OUTPUT device if no buffers have
> - * been queued yet.
> + * Cannot start streaming if driver requires queued buffers.
> */
> - if (V4L2_TYPE_IS_OUTPUT(q->type)) {
> + if (!(q->io_flags & VB2_STREAMON_WITHOUT_BUFFERS)) {
> if (list_empty(&q->queued_list)) {
> - dprintk(1, "streamon: no output buffers queued\n");
> + dprintk(1, "streamon: no buffers queued\n");
> return -EINVAL;
> }
> }
>
> /*
> + * If any buffers were queued before streamon,
> + * we can now pass them to driver for processing.
> + */
> + list_for_each_entry(vb, &q->queued_list, queued_entry)
> + __enqueue_in_driver(vb);
> +
> + /*
> * Let driver notice that streaming state has been enabled.
> */
> ret = call_qop(q, start_streaming, q);
Am I missing something? What is the purpose of this flag? Why not let the
driver check in start_streaming whether any buffers have been queued and
return -EINVAL if there aren't any? Between setting a flag or just doing the
test in start_streaming I would prefer just doing the test.
To make it even easier you can perhaps add an extra argument to
start_streaming with the number of buffers that are already queued.
I can't help thinking that this is made more difficult than it really is.
Regards,
Hans
> @@ -1157,13 +1163,6 @@ int vb2_streamon(struct vb2_queue *q, enum
v4l2_buf_type type)
>
> q->streaming = 1;
>
> - /*
> - * If any buffers were queued before streamon,
> - * we can now pass them to driver for processing.
> - */
> - list_for_each_entry(vb, &q->queued_list, queued_entry)
> - __enqueue_in_driver(vb);
> -
> dprintk(3, "Streamon successful\n");
> return 0;
> }
> diff --git a/drivers/media/video/vivi.c b/drivers/media/video/vivi.c
> index 2238a61..e740a44 100644
> --- a/drivers/media/video/vivi.c
> +++ b/drivers/media/video/vivi.c
> @@ -1232,7 +1232,7 @@ static int __init vivi_create_instance(int inst)
> q = &dev->vb_vidq;
> memset(q, 0, sizeof(dev->vb_vidq));
> q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> - q->io_modes = VB2_MMAP | VB2_USERPTR | VB2_READ;
> + q->io_modes = VB2_MMAP | VB2_READ | VB2_STREAMON_WITHOUT_BUFFERS;
> q->drv_priv = dev;
> q->buf_struct_size = sizeof(struct vivi_buffer);
> q->ops = &vivi_video_qops;
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index f87472a..cdc0558 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -84,12 +84,15 @@ struct vb2_plane {
> * @VB2_USERPTR: driver supports USERPTR with streaming API
> * @VB2_READ: driver supports read() style access
> * @VB2_WRITE: driver supports write() style access
> + * @VB2_STREAMON_WITHOUT_BUFFERS: driver supports stream_on() without
buffers
> + * queued
> */
> enum vb2_io_modes {
> - VB2_MMAP = (1 << 0),
> - VB2_USERPTR = (1 << 1),
> - VB2_READ = (1 << 2),
> - VB2_WRITE = (1 << 3),
> + VB2_MMAP = (1 << 0),
> + VB2_USERPTR = (1 << 1),
> + VB2_READ = (1 << 2),
> + VB2_WRITE = (1 << 3),
> + VB2_STREAMON_WITHOUT_BUFFERS = (1 << 16),
> };
>
> /**
> --
> 1.7.1.569.g6f426
>
> --
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