Re: [PATCH v5 4/7] uvcvideo: Tell the user space we're using start-of-exposure timestamps

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

Thank you for the patch.

On Saturday 15 February 2014 22:53:02 Sakari Ailus wrote:
> The UVC device provided timestamps are taken from the clock once the
> exposure of the frame has begun, not when the reception of the frame would
> have been finished as almost anywhere else. Show this to the user space by
> using V4L2_BUF_FLAG_TSTAMP_SRC_SOE buffer flag.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>

Strictly speaking that's not entirely true, as some devices don't bother 
reporting a hardware timestamp. However, in practice, most devices should 
behave correctly, so that flag is definitely better.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/media/usb/uvc/uvc_queue.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_queue.c
> b/drivers/media/usb/uvc/uvc_queue.c index cd962be..a9292d2 100644
> --- a/drivers/media/usb/uvc/uvc_queue.c
> +++ b/drivers/media/usb/uvc/uvc_queue.c
> @@ -149,7 +149,8 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum
> v4l2_buf_type type, queue->queue.buf_struct_size = sizeof(struct
> uvc_buffer);
>  	queue->queue.ops = &uvc_queue_qops;
>  	queue->queue.mem_ops = &vb2_vmalloc_memops;
> -	queue->queue.timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	queue->queue.timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
> +		| V4L2_BUF_FLAG_TSTAMP_SRC_SOE;
>  	ret = vb2_queue_init(&queue->queue);
>  	if (ret)
>  		return ret;

-- 
Regards,

Laurent Pinchart