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

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Message-ID: <d449ae59-11a2-436e-a51c-cf2fa3657ba2@kernel.org>
Date: Mon, 30 Jun 2025 15:12:38 +0200
From: Hans de Goede <hansg@...nel.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
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()

Hi,

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 ?

Regards,

Hans