linux-kernel - Re: [PATCH v4 3/5] media: uvcvideo: Split uvc_stop

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Message-ID: <20250630132438.GC23516@pendragon.ideasonboard.com>
Date: Mon, 30 Jun 2025 16:24:38 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Hans de Goede <hansg@...nel.org>
Cc: Hans Verkuil <hverkuil@...all.nl>,
	Ricardo Ribalda <ribalda@...omium.org>,
	Hans de Goede <hdegoede@...hat.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/5] media: uvcvideo: Split uvc_stop_streaming()

On Mon, Jun 30, 2025 at 03:12:38PM +0200, Hans de Goede wrote:
> On 30-Jun-25 3:10 PM, Laurent Pinchart wrote:
> > On Mon, Jun 30, 2025 at 02:59:05PM +0200, Hans de Goede wrote:
> >> On 17-Jun-25 11:27 AM, Hans Verkuil wrote:
> >>> On 16/06/2025 17:24, Ricardo Ribalda wrote:
> >>>> uvc_stop_streaming() is used for meta and video nodes. Split the function
> >>>> in two to avoid confusion.
> >>>>
> >>>> Use this opportunity to rename uvc_start_streaming() to
> >>>> uvc_start_streaming_video(), as it is only called by the video nodes.
> >>>>
> >>>> Reviewed-by: Hans de Goede <hansg@...nel.org>
> >>>> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> >>>> ---
> >>>>  drivers/media/usb/uvc/uvc_queue.c | 22 +++++++++++++++-------
> >>>>  1 file changed, 15 insertions(+), 7 deletions(-)
> >>>>
> >>>> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> >>>> index 8f9737ac729546683ca48f5e71ce3dfacbae2926..3f357c2d48cfd258c26f0342007d1d12f1e01007 100644
> >>>> --- a/drivers/media/usb/uvc/uvc_queue.c
> >>>> +++ b/drivers/media/usb/uvc/uvc_queue.c
> >>>> @@ -167,7 +167,7 @@ static void uvc_buffer_finish(struct vb2_buffer *vb)
> >>>>  		uvc_video_clock_update(stream, vbuf, buf);
> >>>>  }
> >>>>  
> >>>> -static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
> >>>> +static int uvc_start_streaming_video(struct vb2_queue *vq, unsigned int count)
> >>>>  {
> >>>>  	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> >>>>  	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
> >>>> @@ -186,14 +186,22 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
> >>>>  	return ret;
> >>>>  }
> >>>>  
> >>>> -static void uvc_stop_streaming(struct vb2_queue *vq)
> >>>> +static void uvc_stop_streaming_video(struct vb2_queue *vq)
> >>>>  {
> >>>>  	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> >>>>  
> >>>>  	lockdep_assert_irqs_enabled();
> >>>>  
> >>>> -	if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
> >>>> -		uvc_video_stop_streaming(uvc_queue_to_stream(queue));
> >>>> +	uvc_video_stop_streaming(uvc_queue_to_stream(queue));
> >>>> +
> >>>> +	uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
> >>>> +}
> >>>> +
> >>>> +static void uvc_stop_streaming_meta(struct vb2_queue *vq)
> >>>> +{
> >>>> +	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> >>>> +
> >>>> +	lockdep_assert_irqs_enabled();
> >>>>  
> >>>>  	uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
> >>>>  }
> >>>> @@ -203,15 +211,15 @@ static const struct vb2_ops uvc_queue_qops = {
> >>>>  	.buf_prepare = uvc_buffer_prepare,
> >>>>  	.buf_queue = uvc_buffer_queue,
> >>>>  	.buf_finish = uvc_buffer_finish,
> >>>> -	.start_streaming = uvc_start_streaming,
> >>>> -	.stop_streaming = uvc_stop_streaming,
> >>>> +	.start_streaming = uvc_start_streaming_video,
> >>>> +	.stop_streaming = uvc_stop_streaming_video,
> >>>>  };
> >>>>  
> >>>>  static const struct vb2_ops uvc_meta_queue_qops = {
> >>>>  	.queue_setup = uvc_queue_setup,
> >>>>  	.buf_prepare = uvc_buffer_prepare,
> >>>>  	.buf_queue = uvc_buffer_queue,
> >>>> -	.stop_streaming = uvc_stop_streaming,
> >>>> +	.stop_streaming = uvc_stop_streaming_meta,
> >>>>  };
> >>>
> >>> I think there should be a comment stating that the metadata stream
> >>> expects that video is streaming, it does not start streaming by itself.
> >>>
> >>> Something like:
> >>>
> >>> 	/*
> >>> 	 * .start_streaming is not provided here. Metadata relies on
> >>> 	 * video streaming being active. If video isn't streaming, then
> >>> 	 * no metadata will arrive either.
> >>> 	 */
> >>>
> >>> It's unexpected that there is no start_streaming for metadata, so a
> >>> comment wouldn't hurt.
> >>
> >> I've added this comment while merging this series and I've now pushed
> >> the entire series to uvc.git/for-next .
> >>
> >> BTW it seems that both uvc.git/next and uvc.git/for-next are in
> >> use now?  With uvc.git/next seemingly following media-commiters/next ?
> > 
> > As far as I understand, some jobs in the media CI use the next branch,
> > for instance the bisect job that tries to compile every commit uses the
> > next branch as a base. We therefore need to keep the next branch
> > up-to-date, mirroring upstream.
> 
> Ok, so we have the next branch mirroring upstream and then we
> use for-next to merge new patches as I've just done ?

Sounds good.

-- 
Regards,

Laurent Pinchart