Re: [PATCH] media: uvcvideo: Add a stream backpointer in uvc_video_queue

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

Hi Ricardo,

Thank you for the patch.

On Wed, Mar 18, 2026 at 08:22:36PM +0000, Ricardo Ribalda wrote:
> It is less prone to errors if we add a backpointer to stream from
> struct uvc_video_queue.
> 
> Refactor the code.
> 
> Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>

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

> ---
> Tested in real hardware with yavta:
> (console A) # yavta -c /dev/video1 
> (console B) # yavta -c /dev/video0
> It would be great if we add it as a follow-up patch to the already
> merged series.
> 
> Thanks!
> 
>  drivers/media/usb/uvc/uvc_driver.c |  2 +-
>  drivers/media/usb/uvc/uvc_isight.c |  3 +--
>  drivers/media/usb/uvc/uvc_queue.c  | 15 ++++++++-------
>  drivers/media/usb/uvc/uvcvideo.h   | 12 +++---------
>  4 files changed, 13 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index b0ca81d924b6..017b1f4ae3ab 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -2033,7 +2033,7 @@ int uvc_register_video_device(struct uvc_device *dev,
>  	int ret;
>  
>  	/* Initialize the video buffers queue. */
> -	ret = uvc_queue_init(queue, type);
> +	ret = uvc_queue_init(stream, queue, type);
>  	if (ret)
>  		return ret;
>  
> diff --git a/drivers/media/usb/uvc/uvc_isight.c b/drivers/media/usb/uvc/uvc_isight.c
> index ea9dc31dfbad..bb3e13c0d5a6 100644
> --- a/drivers/media/usb/uvc/uvc_isight.c
> +++ b/drivers/media/usb/uvc/uvc_isight.c
> @@ -41,8 +41,7 @@ static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf,
>  		0xde, 0xad, 0xfa, 0xce
>  	};
>  
> -	struct uvc_streaming *stream = uvc_queue_to_stream(queue,
> -						V4L2_BUF_TYPE_VIDEO_CAPTURE);
> +	struct uvc_streaming *stream = queue->stream;
>  	unsigned int maxlen, nbytes;
>  	u8 *mem;
>  	int is_header = 0;
> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> index 89206f761006..3c002c8f442f 100644
> --- a/drivers/media/usb/uvc/uvc_queue.c
> +++ b/drivers/media/usb/uvc/uvc_queue.c
> @@ -78,7 +78,7 @@ static int uvc_queue_setup(struct vb2_queue *vq,
>  			   unsigned int sizes[], struct device *alloc_devs[])
>  {
>  	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> -	struct uvc_streaming *stream = uvc_queue_to_stream(queue, vq->type);
> +	struct uvc_streaming *stream = queue->stream;
>  	unsigned int size;
>  
>  	switch (vq->type) {
> @@ -112,7 +112,7 @@ static int uvc_buffer_prepare(struct vb2_buffer *vb)
>  
>  	if (vb->type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
>  	    vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0)) {
> -		uvc_dbg(uvc_queue_to_stream(queue, vb->type)->dev, CAPTURE,
> +		uvc_dbg(queue->stream->dev, CAPTURE,
>  			"[E] Bytes used out of bounds\n");
>  		return -EINVAL;
>  	}
> @@ -159,17 +159,16 @@ static void uvc_buffer_finish(struct vb2_buffer *vb)
>  {
>  	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
>  	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
> -	struct uvc_streaming *stream = uvc_queue_to_stream(queue, vb->type);
>  	struct uvc_buffer *buf = uvc_vbuf_to_buffer(vbuf);
>  
>  	if (vb->state == VB2_BUF_STATE_DONE)
> -		uvc_video_clock_update(stream, vbuf, buf);
> +		uvc_video_clock_update(queue->stream, vbuf, buf);
>  }
>  
>  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, vq->type);
> +	struct uvc_streaming *stream = queue->stream;
>  	int ret;
>  
>  	lockdep_assert_irqs_enabled();
> @@ -196,7 +195,7 @@ static int uvc_start_streaming_video(struct vb2_queue *vq, unsigned int count)
>  static void uvc_stop_streaming_video(struct vb2_queue *vq)
>  {
>  	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> -	struct uvc_streaming *stream = uvc_queue_to_stream(queue, vq->type);
> +	struct uvc_streaming *stream = queue->stream;
>  
>  	lockdep_assert_irqs_enabled();
>  
> @@ -237,10 +236,12 @@ static const struct vb2_ops uvc_meta_queue_qops = {
>  	.stop_streaming = uvc_stop_streaming_meta,
>  };
>  
> -int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> +int uvc_queue_init(struct uvc_streaming *stream, struct uvc_video_queue *queue,
> +		   enum v4l2_buf_type type)
>  {
>  	int ret;
>  
> +	queue->stream = stream;
>  	queue->queue.type = type;
>  	queue->queue.io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF;
>  	queue->queue.drv_priv = queue;
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 5ba698d2a23d..0a0c01b2420f 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -331,6 +331,7 @@ struct uvc_buffer {
>  #define UVC_QUEUE_DISCONNECTED		(1 << 0)
>  
>  struct uvc_video_queue {
> +	struct uvc_streaming *stream;
>  	struct video_device vdev;
>  	struct vb2_queue queue;
>  	struct mutex mutex;			/*
> @@ -692,7 +693,8 @@ do {									\
>  struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
>  
>  /* Video buffers queue management. */
> -int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> +int uvc_queue_init(struct uvc_streaming *stream, struct uvc_video_queue *queue,
> +		   enum v4l2_buf_type type);
>  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
>  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
>  					 struct uvc_buffer *buf);
> @@ -703,14 +705,6 @@ static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
>  	return vb2_is_streaming(&queue->queue);
>  }
>  
> -static inline struct uvc_streaming *
> -uvc_queue_to_stream(struct uvc_video_queue *queue, unsigned int type)
> -{
> -	if (type == V4L2_BUF_TYPE_META_CAPTURE)
> -		return container_of(queue, struct uvc_streaming, meta.queue);
> -	return container_of(queue, struct uvc_streaming, queue);
> -}
> -
>  /* V4L2 interface */
>  extern const struct v4l2_ioctl_ops uvc_ioctl_ops;
>  extern const struct v4l2_file_operations uvc_fops;

-- 
Regards,

Laurent Pinchart