[PATCH v3 3/9] dt-bindings: regulator: Document MediaTek MT6392 PMIC Regulators

[Chen-Yu Tsai]

On Thu, Mar 19, 2026 at 6:14 AM Krzysztof Kozlowski <krzk at kernel.org> wrote:
>
> On 18/03/2026 22:25, Luca Leonardo Scorcia wrote:
> >>
> >> Drop compatible. Regulator nodes do not have compatibles.
> >
> > Thanks for this comment. It took me a while to understand what you
> > meant as most of the MediaTek PMIC regulator drivers still require the
> > compatible node to probe, including MT6397 that was the template for
> > this patch. I compared the driver to MT6359 that does not use it and I
> > am now working on the driver to not rely on it.
> >
> >> With this, you can also drop example as it won't be used.
> >
> > Just to be sure - do you mean remove the compatible attribute from the
> > example, or the whole example section?
>
> The entire example because without the compatible it will be no-op.
>
> >
> >>> +
> >>> +patternProperties:
> >>> +  "^(buck_)?v(core|proc|sys)$":
> >>
> >> Nope, underscores are not allowed. Use only hyphens.
> >
> > Got it. I will actually completely remove the (buck_|ldo_) prefix
> > altogether as suggested in another comment.
> >
> >>> +  "^(ldo_)?v(adc18|camio|cn18|io18)$":
> >>> +    description: LDOs with fixed 1.8V output
> >>
> >> If fixed, then encode it in the schema - min/max microvolt.
> >
> > If possible I'd like some clarification here. According to Chen-Yu
> > Tsai comment [1], dtsi shouldn't contain voltage constraints. The way
>
> That's odd, because long time in the past I heard that DTS must
> absolutely set min/max constraints, because these are real hardware
> (board) constraints for each regulator, unlike the generic and broad
> ones from the driver.
>
> IOW, driver has what datasheet tells. DTS has what actually should be used.
>
> Also, I did not actually require to make min/max required, just they
> have to be specific/constrained.
>
> > I understood this is that electrical constraints are a matter of the
> > actual board layout, so if adjustments are needed they have to be in
> > the board dts. But you also specify "If fixed", so maybe there's an
> > exception to this rule when the constraint is "absolute" and boards
> > can't actually set a different value?
>
> Now I am confused. You wrote - LDOs with fixed 1.8V output - so board
> cannot set it to 2.0V for example. They are affixed. This regulator
> CANNOT physically produce anything else.

As you said, it cannot physically produce anything else. IMO it doesn't
even need voltage constraints as it is already implied by the model and
regulator output, in which case I would actually recommend rejecting
min/max voltage being added to this node.


ChenYu