linux-kernel - Re: [PATCH] media: pci: mgb4: Fix timings comparison in VIDIOC_S_DV

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Message-ID: <7ce56415-77d9-4952-bf7a-a8610d393ded@kernel.org>
Date: Mon, 25 Aug 2025 17:03:37 +0200
From: Hans Verkuil <hverkuil+cisco@...nel.org>
To: tumic@...see.org, Mauro Carvalho Chehab <mchehab@...nel.org>,
 Hans Verkuil <hverkuil@...all.nl>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
 Martin Tůma <martin.tuma@...iteqautomotive.com>
Subject: Re: [PATCH] media: pci: mgb4: Fix timings comparison in
 VIDIOC_S_DV_TIMINGS

On 04/08/2025 11:20, tumic@...see.org wrote:
> From: Martin Tůma <martin.tuma@...iteqautomotive.com>
> 
> Compare the whole v4l2_bt_timings struct, not just the width/height when
> setting new timings. Timings with the same resolution and different
> pixelclock can now be properly set.
> 
> Signed-off-by: Martin Tůma <martin.tuma@...iteqautomotive.com>
> ---
>  drivers/media/pci/mgb4/mgb4_vin.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/pci/mgb4/mgb4_vin.c b/drivers/media/pci/mgb4/mgb4_vin.c
> index 989e93f67f75..15182549d108 100644
> --- a/drivers/media/pci/mgb4/mgb4_vin.c
> +++ b/drivers/media/pci/mgb4/mgb4_vin.c
> @@ -610,8 +610,8 @@ static int vidioc_s_dv_timings(struct file *file, void *fh,
>  	    timings->bt.height < video_timings_cap.bt.min_height ||
>  	    timings->bt.height > video_timings_cap.bt.max_height)
>  		return -EINVAL;
> -	if (timings->bt.width == vindev->timings.bt.width &&
> -	    timings->bt.height == vindev->timings.bt.height)
> +	if (!memcmp(&timings->bt, &vindev->timings.bt,
> +		    sizeof(struct v4l2_bt_timings)))

I would recommend calling v4l2_match_dv_timings() instead.
Otherwise you would also match on the reserved fields and 'standards'
and 'flags' fields.

Regards,

	Hans

>  		return 0;
>  	if (vb2_is_busy(&vindev->queue))
>  		return -EBUSY;
> 
> base-commit: d968e50b5c26642754492dea23cbd3592bde62d8