linux-kernel - Re: [PATCH 1/2] dt-bindings: hwmon: ti,ina2xx: Add alert-polarity property

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Date: Thu, 30 May 2024 10:18:08 +0200
From: Amna Waseem <Amna.Waseem@...s.com>
To: Guenter Roeck <linux@...ck-us.net>, Krzysztof Kozlowski
 <krzk@...nel.org>, Jean Delvare <jdelvare@...e.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, kernel@...s.com
Subject: Re: [PATCH 1/2] dt-bindings: hwmon: ti,ina2xx: Add alert-polarity
 property

On 5/29/24 16:01, Guenter Roeck wrote:
> On 5/29/24 00:07, Krzysztof Kozlowski wrote:
>> On 29/05/2024 08:07, Amna Waseem wrote:
>>> Add a property to the binding to configure the Alert Polarity.
>>> Alert pin is asserted based on the value of Alert Polarity bit of
>>> Mask/Enable register. It is by default 0 which means Alert pin is
>>> configured to be active low. To configure it to active high, set
>>> alert-polarity property value to 1.
>>>
>>> Signed-off-by: Amna Waseem <Amna.Waseem@...s.com>
>>> ---
>>>   Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml | 9 +++++++++
>>>   1 file changed, 9 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml 
>>> b/Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml
>>> index df86c2c92037..a3f0fd71fcc6 100644
>>> --- a/Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml
>>> +++ b/Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml
>>> @@ -66,6 +66,14 @@ properties:
>>>       description: phandle to the regulator that provides the VS 
>>> supply typically
>>>         in range from 2.7 V to 5.5 V.
>>>   +  alert-polarity:
>>
>> Missing vendor prefix.
>>
>
> Are you sure you want a vendor prefix here ? Reason for asking is that
> many hardware monitoring chips have configurable alert or interrupt 
> polarity,
> only the name is different. Some examples are the JC42.4 standard ("event
> polarity"), adt7410/adt7420 "interrupt polarity", MAX31827 ("alarm 
> polarity"),
> or DS1621 ("output polarity"). We even have a vendor property, 
> "adi,alarm-pol",
> used for MAX31827.
>
> Secondary problem is that not all chips of the series support this
> configuration. INA209 has a configurable "warning polarity", but the
> warning pin and the smbus alert pin are two different pins.
> INA219 and INA220 do not have alert or interrupt output pins.
> Only INA226, INA230, INA231, INA238, and INA260 support configurable
> alert polarity.
>
> Thanks,
> Guenter

I agree with not using vendor prefix with alert-polarity property. 
@Krzysztof Kozlowski what do you suggest?

Amna

>>> +    description: |
>>
>> Do not need '|' unless you need to preserve formatting.
>>
>>> +      Alert polarity bit value of Mask/Enable register. Alert pin 
>>> is asserted
>>> +      based on the value of Alert polarity Bit. Default value is 
>>> active low.
>>> +      0 selects active low, 1 selects active high.
>>
>> Just use string, easier to read. But for sure do not introduce different
>> values than we already have - GPIO HIGH is 0, not 1.
>>
>>
>>
>> Best regards,
>> Krzysztof
>>
>