linux-kernel - Re: [PATCH v5 1/2] dt-bindings: adc: provide max34408/9 device tree binding document

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Message-ID: <9996a912-7b4e-4247-bb8a-716782fbcc2a@linaro.org>
Date:   Fri, 13 Oct 2023 11:53:33 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc:     Ivan Mikhaylov <fr0st61te@...il.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v5 1/2] dt-bindings: adc: provide max34408/9 device tree
 binding document

On 13/10/2023 11:09, Jonathan Cameron wrote:
>>>>>>>> +  shtdn-enable-gpios:      
>>>>>>>
>>>>>>> I guess the review crossed with you sending v5.  There is some
>>>>>>> feedback on v4 you need
>>>>>>> to address here.      
>>>>>>
>>>>>> Jonathan, I thought I did, I've changed ena to powerdown-gpios from
>>>>>> Krzysztof's comments but about this one pin I'm still not sure, it
>>>>>> looks like *-enable-gpios (like in *-enable-gpios pins in
>>>>>> iio/frequency/adi,adf4377.yaml) pin or is it not? Or maybe any
>>>>>> other
>>>>>> suggestions about naming of this one?
>>>>>>
>>>>>> Thanks.    
>>>>>
>>>>> shutdown-gpios and make the sense (active high / low) such that
>>>>> setting
>>>>> it results in teh device being shut down.
>>>>> Or treat it as an enable and enable-gpios
>>>>>
>>>>> Something that indicates both shutdown and enable is confusing ;)
>>>>>
>>>>> Jonathan    
>>>>
>>>>
>>>> Jonathan, then I make these changes:
>>>>
>>>> powerdown-gpios: -> output-enable:  
>>> Needs to retain the gpios bit as we want the standard gpio stuff to pick
>>> them up. I'm not that keen on output-enable-gpios though.  The activity
>>> here is very much 'shutdown because of error or not enabled' I think.
>>> So perhaps we flip the sense and document that it needs to be active low?
>>>   
>>>> shtdn-enable-gpios: -> enable-gpios:
>>>>
>>>> Is it ok?  
>>>
>>> Conor, Rob, Krzysztof - you probably have a better insight into this than
>>> I do.
>>>   
>>
>> "enable-gpios" are for turning on a specific feature, not powering
>> on/off entire device. For example to enable regulator output.
>>
>> "powerdown-gpios" are for turning device on/off.
>>
>> I don't know what do you have in your device.
> Ok. Sounds like that what is enable-gpios above should be shutdown-gpios.

shutdown-gpios sounds exactly the same as powerdown-gpios and it is
already used in exactly same context.

> The other case is a device output indicating whether the device is
> shutdown.  That can happen because it was told to do so (via the other gpio),
> or because it is in an error state. What's a good naming convention for that?

There is no convention and I did not see such case so far.
powerdown-status-gpios? powerdown-state-gpios?



Best regards,
Krzysztof