Re: [PATCH 1/3] media: uvcvideo: Enable VB2_DMABUF for metadata stream

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

On Mon, Mar 09, 2026 at 03:01:54PM +0000, Ricardo Ribalda wrote:
> The UVC driver has two video streams, one for the frames and another one
> for the metadata. Both streams share most of the codebase, but only the
> data stream declares support for DMABUF transfer mode.
> 
> I have tried the DMABUF transfer mode with CONFIG_DMABUF_HEAPS_SYSTEM
> and the frames looked correct.
> 
> This patch announces the support for DMABUF for the metadata stream.
> This is useful for apps/HALs that only want to support DMABUF.

Is that something you plan to use in Android ?

> Cc: stable@vger.kernel.org
> Fixes: 088ead2552458 ("media: uvcvideo: Add a metadata device node")
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/usb/uvc/uvc_queue.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> index 8b8f44b4a045..0eddd4f872ca 100644
> --- a/drivers/media/usb/uvc/uvc_queue.c
> +++ b/drivers/media/usb/uvc/uvc_queue.c
> @@ -243,7 +243,7 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>  	int ret;
>  
>  	queue->queue.type = type;
> -	queue->queue.io_modes = VB2_MMAP | VB2_USERPTR;
> +	queue->queue.io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF;

One day we should start warning about USERPTR being deprecated.

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

>  	queue->queue.drv_priv = queue;
>  	queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
>  	queue->queue.mem_ops = &vb2_vmalloc_memops;
> @@ -256,7 +256,6 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>  		queue->queue.ops = &uvc_meta_queue_qops;
>  		break;
>  	default:
> -		queue->queue.io_modes |= VB2_DMABUF;
>  		queue->queue.ops = &uvc_queue_qops;
>  		break;
>  	}
> 

-- 
Regards,

Laurent Pinchart