Re: [PATCH v1] media: i2c: alvium: Fix controls for WB/AWB

[Sakari Ailus]

Hi Martin,

Thanks for the patch.

On Tue, May 05, 2026 at 04:25:10PM +0200, Martin Hecht wrote:
> With that patch the controls for red-balance and blue-balance were created
> only if the particular camera supports that. Otherwise the pointers on
> the control variable are initialized with NULL to prevent side effects for
> clustering with AWB control.
> 
> Fixes: 0a7af872915e ("media: i2c: Add support for alvium camera")
> Signed-off-by: Martin Hecht <mhecht73@xxxxxxxxx>
> ---
>  drivers/media/i2c/alvium-csi2.c | 37 ++++++++++++++++++++-------------
>  1 file changed, 22 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/media/i2c/alvium-csi2.c b/drivers/media/i2c/alvium-csi2.c
> index b62b45a4f2fc..4c6934e9e177 100644
> --- a/drivers/media/i2c/alvium-csi2.c
> +++ b/drivers/media/i2c/alvium-csi2.c
> @@ -2108,26 +2108,33 @@ static int alvium_ctrl_init(struct alvium_dev *alvium)
>  						  0, 0, &alvium->link_freq);
>  	ctrls->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;

This is a problem. Can you move setting the flags after checking the
handler's error status? The functions adding controls may fail and this is
simply a missing error check.

Can you submit a fix, with a Fixes: tag and this patch should be rebased on
the fix, please?

>  
> +	if (alvium->avail_ft.whiteb) {
> +		ctrls->blue_balance = v4l2_ctrl_new_std(hdl, ops,
> +							V4L2_CID_BLUE_BALANCE,
> +							alvium->min_bbalance,
> +							alvium->max_bbalance,
> +							alvium->inc_bbalance,
> +							alvium->dft_bbalance);
> +		ctrls->red_balance = v4l2_ctrl_new_std(hdl, ops,
> +						       V4L2_CID_RED_BALANCE,
> +						       alvium->min_rbalance,
> +						       alvium->max_rbalance,
> +						       alvium->inc_rbalance,
> +						       alvium->dft_rbalance);
> +	} else {
> +		/* set to NULL for v4l2_ctrl_auto_cluster if not existing */
> +		ctrls->blue_balance	= NULL;
> +		ctrls->red_balance = NULL;

Aren't the two NULL already before this?

> +	}
> +
>  	/* Auto/manual white balance */
>  	if (alvium->avail_ft.auto_whiteb) {
>  		ctrls->auto_wb = v4l2_ctrl_new_std(hdl, ops,
>  						   V4L2_CID_AUTO_WHITE_BALANCE,
>  						   0, 1, 1, 1);
> -		v4l2_ctrl_auto_cluster(3, &ctrls->auto_wb, 0, false);
> -	}
> -
> -	ctrls->blue_balance = v4l2_ctrl_new_std(hdl, ops,
> -						V4L2_CID_BLUE_BALANCE,
> -						alvium->min_bbalance,
> -						alvium->max_bbalance,
> -						alvium->inc_bbalance,
> -						alvium->dft_bbalance);
> -	ctrls->red_balance = v4l2_ctrl_new_std(hdl, ops,
> -					       V4L2_CID_RED_BALANCE,
> -					       alvium->min_rbalance,
> -					       alvium->max_rbalance,
> -					       alvium->inc_rbalance,
> -					       alvium->dft_rbalance);
> +
> +		v4l2_ctrl_auto_cluster(3, &ctrls->auto_wb, 0, true);
> +	}
>  
>  	/* Auto/manual exposure */
>  	if (alvium->avail_ft.auto_exp) {

-- 
Kind regards,

Sakari Ailus