[PATCH] hwmon: (ina2xx) make regulator 'vs' support optional

[PATCH] hwmon: (ina2xx) make regulator 'vs' support optional

[Ciprian Costea]

From: Ciprian Marian Costea <ciprianmarian.costea@oss.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@nxp.com>
Signed-off-by: Florin Buica <florin.buica@nxp.com>
Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.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 = devm_regulator_get_enable(dev, "vs");
-	if (ret)
+	ret = devm_regulator_get_enable_optional(dev, "vs");
+	if (ret < 0 && ret != -ENODEV)
 		return dev_err_probe(dev, ret, "failed to enable vs regulator\n");
 
 	ret = ina2xx_init(dev, data);
-- 
2.45.2

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

[Guenter Roeck]

On 4/3/25 03:15, Ciprian Costea wrote:
> From: Ciprian Marian Costea <ciprianmarian.costea@oss.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@nxp.com>
> Signed-off-by: Florin Buica <florin.buica@nxp.com>
> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.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

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

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

[Ciprian Marian Costea]

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@oss.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@nxp.com>
>> Signed-off-by: Florin Buica <florin.buica@nxp.com>
>> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.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);
> 

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

[Guenter Roeck]

On Thu, Apr 03, 2025 at 05:29:26PM +0300, Ciprian Marian Costea wrote:
> 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@oss.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@nxp.com>
> > > Signed-off-by: Florin Buica <florin.buica@nxp.com>
> > > Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.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()'
> 
Yes, but the reasoning you provided is different and suggested that the
current code would not work. Since that is not the case, the change would
be purely cosmetic. Also, I still don't see why the -ENODEV check would be
necessary.

Guenter

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

[Ciprian Marian Costea]

On 4/3/2025 7:06 PM, Guenter Roeck wrote:
> On Thu, Apr 03, 2025 at 05:29:26PM +0300, Ciprian Marian Costea wrote:
>> 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@oss.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@nxp.com>
>>>> Signed-off-by: Florin Buica <florin.buica@nxp.com>
>>>> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.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()'
>>
> Yes, but the reasoning you provided is different and suggested that the
> current code would not work. Since that is not the case, the change would
> be purely cosmetic. Also, I still don't see why the -ENODEV check would be
> necessary.
> 
> Guenter

For boards such as S32G274A-EVB, S32G274A-RDB2 and S32G399A-RDB3 which 
do not have a voltage regulator, 'devm_regulator_get_enable_optional()' 
would return error value -19 (-ENODEV). Also, other usages from the 
Linux Kernel seem to perform the same error check when using 
'devm_regulator_get_enable_optional()' [1], [2] and [3].

This patch would help in S32G2 and S32G3 to not print an unnecessary 
kernel log warning hinting usage of a dummy regulator when such a 
regulator is not required according to the binding.

Would you like me to send a V2 with the commit title updated as follows ?

"
hwmon: (ina2xx) make regulator 'vs' support optional

According to the 'ti,ina2xx' binding, the 'vs-supply' property is 
optional. Furthermore, S32G2/S32G3 based boards which integrate the 
ina231 sensor do not have a dedicated voltage regulator. Thus, making 
regulator support optional would help in avoiding any unnecessary kernel 
log warnings during boot.
"

[1] 
https://elixir.bootlin.com/linux/v6.13.7/source/drivers/iio/adc/ad7625.c#L524-L525
[2] 
https://elixir.bootlin.com/linux/v6.13.7/source/drivers/pci/controller/pcie-rcar-host.c#L982-L983
[3] 
https://elixir.bootlin.com/linux/v6.13.7/source/drivers/iio/adc/ad7944.c#L514-L515

Regards,
Ciprian

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

[Guenter Roeck]

On 4/4/25 01:36, Ciprian Marian Costea wrote:
> On 4/3/2025 7:06 PM, Guenter Roeck wrote:
>> On Thu, Apr 03, 2025 at 05:29:26PM +0300, Ciprian Marian Costea wrote:
>>> 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@oss.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@nxp.com>
>>>>> Signed-off-by: Florin Buica <florin.buica@nxp.com>
>>>>> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.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()'
>>>
>> Yes, but the reasoning you provided is different and suggested that the
>> current code would not work. Since that is not the case, the change would
>> be purely cosmetic. Also, I still don't see why the -ENODEV check would be
>> necessary.
>>
>> Guenter
> 
> For boards such as S32G274A-EVB, S32G274A-RDB2 and S32G399A-RDB3 which do not have a voltage regulator, 'devm_regulator_get_enable_optional()' would return error value -19 (-ENODEV). Also, other usages from the Linux Kernel seem to perform the same error check when using 'devm_regulator_get_enable_optional()' [1], [2] and [3].
> 
> This patch would help in S32G2 and S32G3 to not print an unnecessary kernel log warning hinting usage of a dummy regulator when such a regulator is not required according to the binding.
> 
> Would you like me to send a V2 with the commit title updated as follows ?
> 
> "
> hwmon: (ina2xx) make regulator 'vs' support optional
> 
> According to the 'ti,ina2xx' binding, the 'vs-supply' property is optional. Furthermore, S32G2/S32G3 based boards which integrate the ina231 sensor do not have a dedicated voltage regulator. Thus, making regulator support optional would help in avoiding any unnecessary kernel log warnings during boot.
> "

Make it:

"According to the 'ti,ina2xx' binding, the 'vs-supply' property is optional.
  Use devm_regulator_get_enable_optional() to avoid a kernel warning message
  if the property is not provided.
"

Then add a note to the code explaining that the check for -ENODEV is necessary
because the regulator core returns -ENODEV if the regulator is not available.

Why it makes sense for this function to return -ENODEV if an _optional_ regulator
is not available escapes me, but that is a different issue.

Guenter

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

[Ciprian Marian Costea]

On 4/8/2025 9:07 PM, Guenter Roeck wrote:
> On 4/4/25 01:36, Ciprian Marian Costea wrote:
>> On 4/3/2025 7:06 PM, Guenter Roeck wrote:
>>> On Thu, Apr 03, 2025 at 05:29:26PM +0300, Ciprian Marian Costea wrote:
>>>> 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@oss.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@nxp.com>
>>>>>> Signed-off-by: Florin Buica <florin.buica@nxp.com>
>>>>>> Signed-off-by: Ciprian Marian Costea 
>>>>>> <ciprianmarian.costea@oss.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()'
>>>>
>>> Yes, but the reasoning you provided is different and suggested that the
>>> current code would not work. Since that is not the case, the change 
>>> would
>>> be purely cosmetic. Also, I still don't see why the -ENODEV check 
>>> would be
>>> necessary.
>>>
>>> Guenter
>>
>> For boards such as S32G274A-EVB, S32G274A-RDB2 and S32G399A-RDB3 which 
>> do not have a voltage regulator, 
>> 'devm_regulator_get_enable_optional()' would return error value -19 
>> (-ENODEV). Also, other usages from the Linux Kernel seem to perform 
>> the same error check when using 'devm_regulator_get_enable_optional()' 
>> [1], [2] and [3].
>>
>> This patch would help in S32G2 and S32G3 to not print an unnecessary 
>> kernel log warning hinting usage of a dummy regulator when such a 
>> regulator is not required according to the binding.
>>
>> Would you like me to send a V2 with the commit title updated as follows ?
>>
>> "
>> hwmon: (ina2xx) make regulator 'vs' support optional
>>
>> According to the 'ti,ina2xx' binding, the 'vs-supply' property is 
>> optional. Furthermore, S32G2/S32G3 based boards which integrate the 
>> ina231 sensor do not have a dedicated voltage regulator. Thus, making 
>> regulator support optional would help in avoiding any unnecessary 
>> kernel log warnings during boot.
>> "
> 
> Make it:
> 
> "According to the 'ti,ina2xx' binding, the 'vs-supply' property is 
> optional.
>   Use devm_regulator_get_enable_optional() to avoid a kernel warning 
> message
>   if the property is not provided.
> "
> 
> Then add a note to the code explaining that the check for -ENODEV is 
> necessary
> because the regulator core returns -ENODEV if the regulator is not 
> available.
> 
> Why it makes sense for this function to return -ENODEV if an _optional_ 
> regulator
> is not available escapes me, but that is a different issue.
> 
> Guenter
> 

Hello Guenter,

Thanks for your review & suggestions.
I will send a V2 patch.


Regards,
Ciprian