Re: [PATCH v6 2/4] dt-bindings: hwmon: pmbus: add MPS MPQ8646

On 7/29/26 23:55, Vincent Jardin wrote:
> Hi Guenter,
> 
> Le 29/07/26 21:10, Guenter Roeck a écrit :
>> On 7/29/26 14:51, Vincent Jardin via B4 Relay wrote:
>>> From: Vincent Jardin <[email protected]>
>>>
>>> The MPS MPQ8646 PMBus step-down converter uses the same
>>> mps,vout-fb-divider-ratio-permille property with the same constraints
>>> (maximum 2047, default 706) as the mps,mpq8785, so add its compatible
>>> to the existing schema.
>>>
>>
>> The driver is a separate driver, making this a bit unusual.
>> I'll leave it up to the devicetree maintainers to decide if
>> this should be a new bindings file or not.
> 
> Because of Krzysztof's review of v5: he asked exactly for it
> since mps,mpq8785.yaml already carries the same property, the same
> constraints and the same defaults:
> 
>    see  https://lore.kernel.org/all/20260727-sceptical-finicky-waxbill-d7ecbf@quoll/
>    "...Everything is the same as mps,mpq8785.yam, so why it cannot be added
>    there? Just grow the list of if:then: to cover your specific
>    constraints."
> 
> v5 had it as a separate mps,mpq8646.yaml file. I'll follow whatever
> the DT maintainers prefer, but so should we consider that it complies
> with Krzysztof's argument ?
> 

Yes, and I guess that answers my question.

I'd like to see that documented somewhere for future reference, but either
I don't find it or the documentation is vague.

Again, the question is: if bindings for two devices use the same properties,
but the chips are different enough to warrant separate drivers, should the
bindings be combined into a single bindings file or should the bindings files
be separate ?

As an interesting twist, the actual binding (mps,vout-fb-divider-ratio-permille)
really applies to many PMBus chips, specifically those supporting the
PMBUS_VOUT_SCALE_LOOP command.

Thanks,
Guenter