Re: [PATCH v2 2/2] dt-bindings: hwmon: add MAX31790

[Guenter Roeck]

On 9/22/23 02:53, Conor Dooley wrote:
> On Fri, Sep 22, 2023 at 02:33:06AM +0000, Delphine_CC_Chiu/WYHQ/Wiwynn wrote:
> > > > On Fri, Sep 15, 2023 at 02:29:24PM +0800, Delphine CC Chiu wrote:
>
> > > > > +  pwm-as-tach:
> > > >
> > > > I don't see any other users of this in-tree, so you'd need a vendor
> > > > prefix. That said, I'm once bitten, twice shy about fan related
> > > > properties in hwmon, so I would definitely like Rob to comment on this
> > > > whole binding.
> > >
> > > Please see this[1] and comment on it to ensure it meets your needs.
> > > Otherwise, omit any fan related properties for now.
> > This property could only be used in max31790 driver. Would it be ok if we add
> > vendor prefix like "maxim, pwm-as-tach"?
>
> I think the answer to this is a pretty straightforward no. The goal is
> to create a set of common fan properties that works for multiple
> usecases, not create one specifically for each user...

Another chip with configurable channel configuration is nct7802, where
individual channels can be configured as temperature or voltage sensor.
We are using sensor-type to select the mode in that driver. Maybe something
similar would make sense / be acceptable here.

> > > > +examples:
> > > > +  - |
> > > > +    i2c {
> > > > +      #address-cells = <1>;
> > > > +      #size-cells = <0>;
> > > > +
> > > > +      pwm@20 {
> > > > +        compatible = "maxim,max31790";
> > > > +        reg = <0x20>;
> > > > +        pwm-as-tach = <2 5>;
> > >
> > > This would be <2>, <5>; no?
> > I refer to the other binding documents in hwmon and most of them were using
> > the format like <2 5> as an array.
>
> Which also makes this moot, since it'll be going away.
>
> > > > diff --git a/MAINTAINERS b/MAINTAINERS index
> > > > c8fdd0d03907..97e13b6bf51d 100644
> > > > --- a/MAINTAINERS
> > > > +++ b/MAINTAINERS
> > > > @@ -1371,6 +1371,12 @@ F:
> > >        Documentation/devicetree/bindings/hwmon/adi,max31760.yaml
> > > >   F: Documentation/hwmon/max31760.rst
> > > >   F: drivers/hwmon/max31760.c
> > > >
> > > > +ANALOG DEVICES INC MAX31790 DRIVER
> > > > +M: Delphine CC Chiu  <Delphine_CC_Chiu@xxxxxxxxxx>
> > > > +S: Odd Fixes
> > >
> > > This is a pretty odd status for something you're newly adding.
> > > How come it's not going to be maintained?
> > We are not the authors of this driver but we want to add a feature to
> > config PWM as TACH that was descripted in the datasheet of MAX31790.
> > Should we set the status to maintained?
>
> It's really up to you. I just found it curious & wanted to ask why it
> was that way.

It is misleading because it downgrades the driver from "supported"
(like all other hwmon drivers) to "odd fixes".

Guenter