Re: [PATCH v7 1/3] dt-bindings: hwmon: Document the LTC4283 Swap Controller

["Nuno Sá" <noname.nuno@gmail.com>]

On Mon, 2026-03-23 at 07:33 -0700, Guenter Roeck wrote:
> [ ...]
> > > > +  adi,pgio1-func:
> > > > +    description: Configures the function of the PGIO1 pin.
> > > > +    $ref: /schemas/types.yaml#/definitions/string
> > > > +    enum: [inverted_power_good, power_good, gpio]
> > > > +    default: inverted_power_good
> > > > +
> > > > +  adi,pgio2-func:
> > > > +    description: Configures the function of the PGIO2 pin.
> > > > +    $ref: /schemas/types.yaml#/definitions/string
> > > > +    enum: [inverted_power_good, power_good, gpio, active_current_limiting]
> > > > +    default: inverted_power_good
> > > > +
> > > > +  adi,pgio3-func:
> > > > +    description: Configures the function of the PGIO3 pin.
> > > > +    $ref: /schemas/types.yaml#/definitions/string
> > > > +    enum: [inverted_power_good_input, power_good_input, gpio]
> > > > +    default: inverted_power_good_input
> > > > +
> > > > +  adi,pgio4-func:
> > > > +    description: Configures the function of the PGIO4 pin.
> > > > +    $ref: /schemas/types.yaml#/definitions/string
> > > > +    enum: [inverted_external_fault, external_fault, gpio]
> > > > +    default: inverted_external_fault
> > > > +
> > > > +  adi,gpio-on-adio1:
> > > > +    description: If set, the ADIO1 pin is used as a GPIO.
> > > > +    type: boolean
> > > > +
> > > > +  adi,gpio-on-adio2:
> > > > +    description: If set, the ADIO2 pin is used as a GPIO.
> > > > +    type: boolean
> > > > +
> > > > +  adi,gpio-on-adio3:
> > > > +    description: If set, the ADIO3 pin is used as a GPIO.
> > > > +    type: boolean
> > > > +
> > > > +  adi,gpio-on-adio4:
> > > > +    description: If set, the ADIO4 pin is used as a GPIO.
> > > > +    type: boolean
> > > 
> > > Does this dependency block force a redundant specification of adi,pgio4-func?
> > > The default for adi,pgio4-func is inverted_external_fault, which means the
> > > default hardware state already supports external fault features.
> > > If a device tree legitimately omits adi,pgio4-func to rely on that default,
> > > will it fail schema validation here since the dependencies keyword strictly
> > > checks for the literal presence of properties without injecting defaults?
> > 
> > Fair point. I guess it will fail but the alternative is to not have any constrain at all so
> > maybe worth it to be explicit in here?
> > 
> 
> I don't claim to understand how to define devicetree properties, but
> 
> adi,pgio4-func = <"gpio">
> 
> and
> 
> adi,gpio-on-adio4;
> 
> seem to be equivalent to me, and omitting the first property (because

Not exactly. ADIO4 and PGIO4 are different pins and can be both configured
as GPIOs. ADIO is a boolean because they are either monitored by the ADC (default)
or configured as GPIOs. PGIOs can have additional configurations and hence the
enum.

- Nuno Sá

> it defaults to inverted_external_fault) would cause the second to fail.
> So either both would be necessary or none. If that is correct, what is
> the point of having the adi,gpio-on-adio4 property in the first place ?
> 
> In other words, what is the difference between
> 	adi,pgio4-func = <"gpio">;
> 	adi,gpio-on-adio4;
> 
> and
> 	adi,pgio4-func = <"gpio">;
> (with no boolean property) ?

> 
> Thanks,
> Guenter