linux-kernel - Re: [PATCH v6 2/8] regulator: dt-bindings: Document max8997-pmic nodes

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Message-ID: <20210106145931.GE4752@sirena.org.uk>
Date:   Wed, 6 Jan 2021 14:59:31 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Timon Baetz <timon.baetz@...tonmail.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Lee Jones <lee.jones@...aro.org>,
        Sebastian Reichel <sre@...nel.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v6 2/8] regulator: dt-bindings: Document max8997-pmic
 nodes

On Tue, Jan 05, 2021 at 05:55:29PM +0100, Krzysztof Kozlowski wrote:
> On Mon, Jan 04, 2021 at 09:24:49PM +0000, Mark Brown wrote:

> > I'm not sure I follow, sorry?  Either the core driver can parse the
> > bindings enough to know what children it has or (probably better) it can
> > instantiate the children unconditionally and then the function drivers
> > can figure out if they need to do anything.

> Currently the MFD parent/core driver will instantiate children
> unconditionally.  It would have to be adapted. With proposed bindings -
> nothing to change.  MFD core already does the thing.

We're not talking massive amounts of code here, but we are talking ABI
for a DT update.

> The point is that function drivers should not be even bound, should not
> start to probe. Otherwise if they probe and fail, they will pollute the
> dmesg/probe log with failure. With the failure coming from looking for
> missing of_node or any other condition from parent/core driver.

There will only be an error message if one is printed, if we can do a
definitive -ENODEV there should be no need to print an error.

> > > Another point, is that this reflects the real hardware. The same as we
> > > model entire SoC as multiple children of soc node (with their own
> > > properties), here we represent smaller chip which also has
> > > sub-components.

> > Components we're calling things like "extcon"...

> I am rather thinking about charger, but yes, extcon as well. Either you
> have USB socket (and want to use associated logic) or not.

Right, I'm just saying we don't need to add new device nodes reflecting
implementation details into the DT to do that.

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