linux-kernel - Re: [PATCH v3 6/6] regulator: dt-bindings: rtq2208: Add property to get ldo of RTQ2208 is adjustable or not

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Date: Tue, 14 May 2024 19:01:21 +0100
From: Conor Dooley <conor@...nel.org>
To: Mark Brown <broonie@...nel.org>
Cc: Alina Yu <alina_yu@...htek.com>, lgirdwood@...il.com,
	robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
	conor+dt@...nel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, johnny_lai@...htek.com,
	cy_huang@...htek.com
Subject: Re: [PATCH v3 6/6] regulator: dt-bindings: rtq2208: Add property to
 get ldo of RTQ2208 is adjustable or not

On Tue, May 14, 2024 at 11:34:29AM +0100, Mark Brown wrote:
> On Mon, May 13, 2024 at 05:22:54PM +0100, Conor Dooley wrote:
> > On Fri, May 10, 2024 at 08:06:25PM +0800, Alina Yu wrote:
> 
> > > +            richtek,fixed-microvolt = <1200000>;
> > >              regulator-min-microvolt = <1200000>;
> > >              regulator-max-microvolt = <1200000>;
> 
> > I'm dumb and this example seemed odd to me. Can you explain to me why
> > it is not sufficient to set min-microvolt == max-microvolt to achieve
> > the same thing?
> 
> This is for a special mode where the voltage being configured is out of
> the range usually supported by the regulator, requiring a hardware
> design change to achieve.  The separate property is because otherwise we
> can't distinguish the case where the mode is in use from the case where
> the constraints are nonsense, and we need to handle setting a fixed
> voltage on a configurable regulator differently to there being a
> hardware fixed voltage on a normally configurable regulator.

Cool, I think an improved comment message and description would be
helpful then to describe the desired behaviour that you mention here.
The commit message in particular isn't great:
| Since there is no way to check is ldo is adjustable or not.
| As discussing in v2 series, 'richtek,fixed-microvolt' is added for that.
| user is supposed to know whether vout of ldo is adjustable.

It also doesn't seem like this sort of behaviour would be limited to
Richtek either, should this actually be a common property in
regulator.yaml w/o the vendor prefix?

Cheers,
Conor.

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