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

[Martin Hecht <mhecht73@gmail.com>]

Hi Sakari,

thank you for the comments.

On 5/6/26 11:28, Sakari Ailus wrote:
> 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@gmail.com>
>> ---
>>   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?

I'm preparing a separate fix for that issue. It's the same situation 
also  for some other controls like pixel_rate and link_frequency but not 
only. Can I combine that into one patch for fix only that in 
alvium_ctrl_init?

> 
>>   
>> +	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?

You are right. It's zeroed before because __GFP_ZERO in devm_kzalloc. 
Will remove that redundant code.

> 
>> +	}
>> +
>>   	/* 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) {
> 

BR Martin