On 06/16/17 09:39, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
>
> Implement the needed pieces to let userspace subscribe for
> V4L2_EVENT_BUF_QUEUED events. Videobuf2 will queue the event for the
> DQEVENT ioctl.
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
> ---
> drivers/media/v4l2-core/v4l2-ctrls.c | 6 +++++-
> drivers/media/v4l2-core/videobuf2-core.c | 15 +++++++++++++++
> 2 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index 5aed7bd..f55b5da 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -3435,8 +3435,12 @@ EXPORT_SYMBOL(v4l2_ctrl_log_status);
> int v4l2_ctrl_subscribe_event(struct v4l2_fh *fh,
> const struct v4l2_event_subscription *sub)
> {
> - if (sub->type == V4L2_EVENT_CTRL)
> + switch (sub->type) {
> + case V4L2_EVENT_CTRL:
> return v4l2_event_subscribe(fh, sub, 0, &v4l2_ctrl_sub_ev_ops);
> + case V4L2_EVENT_BUF_QUEUED:
> + return v4l2_event_subscribe(fh, sub, 0, NULL);
This is dangerous. The '0' argument will only allocate room for a single
BUF_QUEUED event. So if two such events are triggered without the application
reading the first event, then the first event will be lost.
I recommend VIDEO_MAX_FRAME instead. I.e. have room for up to the maximum number
of buffers.
> + }
> return -EINVAL;
> }
> EXPORT_SYMBOL(v4l2_ctrl_subscribe_event);
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index 29aa9d4..00d9c35 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -25,6 +25,7 @@
> #include <linux/kthread.h>
>
> #include <media/videobuf2-core.h>
> +#include <media/v4l2-event.h>
> #include <media/v4l2-mc.h>
>
> #include <trace/events/vb2.h>
> @@ -1221,6 +1222,18 @@ static int __prepare_dmabuf(struct vb2_buffer *vb, const void *pb)
> return ret;
> }
>
> +static void vb2_buffer_queued_event(struct vb2_buffer *vb)
> +{
> + struct video_device *vdev = to_video_device(vb->vb2_queue->dev);
> + struct v4l2_event event;
> +
> + memset(&event, 0, sizeof(event));
> + event.type = V4L2_EVENT_BUF_QUEUED;
> + event.u.buf_queued.index = vb->index;
> +
> + v4l2_event_queue(vdev, &event);
> +}
> +
> /**
> * __enqueue_in_driver() - enqueue a vb2_buffer in driver for processing
> */
> @@ -1234,6 +1247,8 @@ static void __enqueue_in_driver(struct vb2_buffer *vb)
> trace_vb2_buf_queue(q, vb);
>
> call_void_vb_qop(vb, buf_queue, vb);
> +
> + vb2_buffer_queued_event(vb);
> }
>
> static int __buf_prepare(struct vb2_buffer *vb, const void *pb)
>
Regards,
Hans
