linux-kernel - Re: [PATCH 3/4] regulator: rt5120: Add PMIC regulator support

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Date:   Fri, 10 Jun 2022 12:03:41 +0100
From:   Mark Brown <broonie@...nel.org>
To:     ChiYuan Huang <u0084500@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Lee Jones <lee.jones@...aro.org>, dmitry.torokhov@...il.com,
        Liam Girdwood <lgirdwood@...il.com>,
        cy_huang <cy_huang@...htek.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, lkml <linux-kernel@...r.kernel.org>,
        linux-input@...r.kernel.org
Subject: Re: [PATCH 3/4] regulator: rt5120: Add PMIC regulator support

On Thu, Jun 09, 2022 at 02:35:07PM +0800, ChiYuan Huang wrote:
> Mark Brown <broonie@...nel.org> 於 2022年6月8日 週三 下午6:12寫道：
> > On Wed, Jun 08, 2022 at 11:15:56AM +0800, ChiYuan Huang wrote:

> > > My excuse. let me explain it.
> > > buck1 voltage range from 600mV to 1393.75mV.
> > > buck2~4/ldo/exten is the fixed regulator.
> > > buck3 and buck4 is fixed by the IC efuse default.
> > > buck2 and ldo is fixed by the external resistor chosen.
> > > exten is designed to connected to the external power.

> > > That's why I cannot directly declared it as the static regulator_desc.

> > So buck 2-4 need some dynamic handling then but the rest can be static -
> > that would be a lot clearer.  You could also have a template for the
> > ones with some dynamic values and just override the few fields that need
> > it.

> Not just buck2/3, buck2/3/4/ldo/exten all need the dynamic handling.

Why do the others need it?

> > > > Drivers should never override constraints passed in by machine drivers,
> > > > if there's validation needed let the core do it.  The same probably
> > > > applies to providing a voltage range for a fixed regulator though that's
> > > > not modifying everything so not such a problem.

> > > Please check the above explanation about each power rails.

> > I'm not sure what you're referencing here?

> Sorry. Let me explain it.

> You mean 'of_parse_cb' must not override constraint.
> But if the regulator is fixed and dynamic, after
> 'of_get_regulation_constraint', apply_uV will be true.
> The is referring to 'fixed.c'

fixed.c is a special case due to legacy issues and being generic, for
normal fixed voltage regulators in a device where we know what they're
fixed to they can just have their voltage hard coded in the driver.  If
there's issues with the machine providing invalid or nonsensical
constraints the driver should just let the core deal with them.

> > > > This is all open coding stuff that's in the core - just provde an
> > > > of_parse_cb() operation and let the core take care of calling it.

> > > Ditto

> > Or here.

> If I put 'of_parce_cb' to make core handling it, the input parameter
> 'init_data' is declared as const.
> I cannot override the 'apply_uV'.
> Right?

Yes, that's by design.

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