linux-kernel - Re: [PATCH V9 4/6] regulator: Add a regulator driver for the PM8008 PMIC

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Message-ID: <CAE-0n51DJyWQKG1AsMjD1wwxx=KCyvyp7-P9BGfiRX=EKjxfdw@mail.gmail.com>
Date:   Wed, 6 Apr 2022 11:16:09 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Satya Priya <quic_c_skakit@...cinc.com>,
        Lee Jones <lee.jones@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_collinsd@...cinc.com,
        quic_subbaram@...cinc.com, quic_jprakash@...cinc.com
Subject: Re: [PATCH V9 4/6] regulator: Add a regulator driver for the PM8008 PMIC

Quoting Mark Brown (2022-04-06 10:27:44)
> On Wed, Apr 06, 2022 at 10:21:01AM -0700, Stephen Boyd wrote:
> > Quoting Mark Brown (2022-04-06 09:36:14)
> > > On Wed, Apr 06, 2022 at 08:51:48AM -0700, Stephen Boyd wrote:
>
> > > > My guess is that this is one IC that responds to multiple i2c addresses.
> > > > The "main" qcom,pm8008 address is 0x8 and that supports things like
> > > > interrupts. Then there's an address for regulators at 0x9 which controls
> > > > the handful of LDOs on the PMIC.
>
> > > So it's like the TI TWL4030 and Palmas - in which case it should
> > > probably be handled similarly?
>
> > How did those work out? I wasn't involved and I don't know what you
> > mean. Do they have multiple i2c addresses they respond to?
>
> Yes, exactly.  The main device uses i2c_new_dummy_device() to
> instantiate the extras when it probes.  See twl-core.c

Cool. That approach sounds good to me. Then the regulators can be child
nodes of the qcom,pm8008 node at i2c address 0x8? It still feels like
making a struct driver for each regulator node is overkill and will
waste memory.

>
> >
> > > Note that the original sumbission was
> > > *also* a MFD subfunction, but using a DT compatible to match the
> > > platform device - this is the first I've heard of this being a separate
> > > I2C function.
>
> > I'm mainly looking at the dts file now. It clearly has two i2c devices
> > at 0x8 and 0x9. Maybe the regulator driver followed the mfd design
> > because the first driver for this device is an mfd.
>
> I'm guessing from the naming that they're also externally described as
> the same device - presumably it's two dies shoved together in the same
> package for some reason without being otherwise joined up.  Is the
> second device geniunely regulators only or does it have anything else
> bundled in there?

I think it's regulators only. Pretty sure I asked qcom this a round or
two ago on this patch series and they said that. Let's wait for Satya to
respond.