Re: [PATCH 2/4] dt-bindings: iio: magnetometer: Add DT binding for Voltafield AF8133J

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

> > > +
> > > +  dvdd-supply:
> > > +    description: |
> > > +      an optional regulator that needs to be on to provide DVDD power (Digital
> > > +      IO power, 1.8V~AVDD) to the sensor.
> > > +
> > > +  mount-matrix:
> > > +    description: an optional 3x3 mounting rotation matrix.
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg  
> > 
> > Any power supply that is required for operation should be listed here (even though
> > we can rely on the stub supplies if it isn't in the DT).
> > I used to think this wasn't necessary, so lots of bindings upstream don't yet
> > have it.  
> 
> By stub supply you mean dummy supply created when the *-supply property is not
> specified in DT? Or something else?

Ah yes. I got the term wrong.
> 
> Because DTC_CHK prints a warning if I make the proerty required in bindings and
> not specify it in DT
> 
> arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone-1.2b.dtb: magnetometer@1c: 'avdd-supply' is a required property
> 	from schema $id: http://devicetree.org/schemas/iio/magnetometer/voltafield,af8133j.yaml#

Provide one, or don't worry about that warning. 

Various discussions have taken place on this over time and end
result is bindings should require them to differentiate from power
supplies that are actually optional.

Jonathan