Re: [PATCH for v6.14] media: rtl2832_sdr: assign vb2 lock before vb2_queue_init

[Arthur Marsh <arthur.marsh@internode.on.net>]

On 25/2/25 01:10, Hans Verkuil wrote:
> Commit c780d01cf1a6 ("media: vb2: vb2_core_queue_init(): sanity check lock and
> wait_prepare/finish") added a sanity check to ensure that if there are no
> wait_prepare/finish callbacks set by the driver, then the vb2_queue lock must
> be set, since otherwise the vb2 core cannot do correct locking.
>
> The rtl2832_sdr.c triggered this warning: it turns out that while the driver
> does set this lock, it sets it too late. So move it up to before the
> vb2_queue_init() call.
>
> Reported-by: Arthur Marsh <arthur.marsh@internode.on.net>
> Fixes: 8fcd2795d22a ("media: rtl2832_sdr: drop vb2_ops_wait_prepare/finish")
> Cc: stable@vger.kernel.org
> Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
> ---
> Arthur, it would be great if you can test this patch!
>
> Regards,
>
> 	Hans
> ---
> diff --git a/drivers/media/dvb-frontends/rtl2832_sdr.c b/drivers/media/dvb-frontends/rtl2832_sdr.c
> index 05254d8717db..0357624968f1 100644
> --- a/drivers/media/dvb-frontends/rtl2832_sdr.c
> +++ b/drivers/media/dvb-frontends/rtl2832_sdr.c
> @@ -1363,6 +1363,7 @@ static int rtl2832_sdr_probe(struct platform_device *pdev)
>   	dev->vb_queue.ops = &rtl2832_sdr_vb2_ops;
>   	dev->vb_queue.mem_ops = &vb2_vmalloc_memops;
>   	dev->vb_queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	dev->vb_queue.lock = &dev->vb_queue_lock;
>   	ret = vb2_queue_init(&dev->vb_queue);
>   	if (ret) {
>   		dev_err(&pdev->dev, "Could not initialize vb2 queue\n");
> @@ -1421,7 +1422,6 @@ static int rtl2832_sdr_probe(struct platform_device *pdev)
>   	/* Init video_device structure */
>   	dev->vdev = rtl2832_sdr_template;
>   	dev->vdev.queue = &dev->vb_queue;
> -	dev->vdev.queue->lock = &dev->vb_queue_lock;
>   	video_set_drvdata(&dev->vdev, dev);
>
>   	/* Register the v4l2_device structure */

I was able to successfully test this patch with DVB-T functionality but 
haven't tested it with SDR functionality:

[   15.946588] usb 1-6: dvb_usb_v2: found a 'Realtek RTL2832U reference 
design' in warm state
[   16.016516] dvbdev: DVB: registering new adapter (Realtek RTL2832U 
reference design)
[   16.122916] rtl2832 3-0010: Realtek RTL2832 successfully attached
[   16.122931] usb 1-6: DVB: registering adapter 0 frontend 0 (Realtek 
RTL2832 (DVB-T))...
[   16.122938] dvbdev: dvb_create_media_entity: media entity 'Realtek 
RTL2832 (DVB-T)' registered.
[   16.417228] rtl2832_sdr rtl2832_sdr.1.auto: Registered as swradio0
[   16.417231] rtl2832_sdr rtl2832_sdr.1.auto: Realtek RTL2832 SDR attached
[   16.417232] rtl2832_sdr rtl2832_sdr.1.auto: SDR API is still slightly 
experimental and functionality changes may follow
[   16.453096] usb 1-6: dvb_usb_v2: 'Realtek RTL2832U reference design' 
successfully initialized and connected

Regards,

Arthur.