linux-kernel - Re: [PATCH] hwmon: (ina2xx) make regulator 'vs' support optional

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Message-ID: <4efff19d-b5e6-49b5-9a15-e4af622c6ebf@oss.nxp.com>
Date: Thu, 3 Apr 2025 17:29:26 +0300
From: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
To: Guenter Roeck <linux@...ck-us.net>, Jean Delvare <jdelvare@...e.com>
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
 NXP S32 Linux <s32@....com>, imx@...ts.linux.dev,
 Christophe Lizzi <clizzi@...hat.com>, Alberto Ruiz <aruizrui@...hat.com>,
 Enric Balletbo <eballetb@...hat.com>, Eric Chanudet <echanude@...hat.com>,
 Florin Buica <florin.buica@....com>
Subject: Re: [PATCH] hwmon: (ina2xx) make regulator 'vs' support optional

On 4/3/2025 3:15 PM, Guenter Roeck wrote:
> On 4/3/25 03:15, Ciprian Costea wrote:
>> From: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
>>
>> S32G2/S32G3 based boards which integrate the ina231 sensor do not have a
>> dedicated voltage regulator.
>>
>> Co-developed-by: Florin Buica <florin.buica@....com>
>> Signed-off-by: Florin Buica <florin.buica@....com>
>> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
>> ---
>>   drivers/hwmon/ina2xx.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
>> index 345fe7db9de9..ab4972f94a8c 100644
>> --- a/drivers/hwmon/ina2xx.c
>> +++ b/drivers/hwmon/ina2xx.c
>> @@ -959,8 +959,8 @@ static int ina2xx_probe(struct i2c_client *client)
>>           return PTR_ERR(data->regmap);
>>       }
>> -    ret = (dev, "vs");
>> -    if (ret)
>> +    ret = devm_regulator_get_enable_optional(dev, "vs");
> 
> devm_regulator_get_enable() should provide a dummy regulator if there is
> no explicit regulator. Why does this not work ?
> 
>> +    if (ret < 0 && ret != -ENODEV)
> 
> Why this added check ?
> 
> I know it used to be necessary if regulator support is disabled,
> but that is no longer the case.
> 
> Guenter
> 

Hello Guenter,

I've just tested and devm_regulator_get_enable() does work as you've 
described, providing a dummy regulator.

But, according to the 'ti,ina2xx' binding [1] I see that the `vs-supply` 
property is not required. Hence wouldn't it be correct for `vs-supply` 
to be optional ? Using 'devm_regulator_get_enable_optional()'


[1] 
https://elixir.bootlin.com/linux/v6.13.7/source/Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml#L78-L80

Regards,
Ciprian

>>           return dev_err_probe(dev, ret, "failed to enable vs 
>> regulator\n");
>>       ret = ina2xx_init(dev, data);
>