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

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Date:   Wed, 6 Apr 2022 18:27:44 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Stephen Boyd <swboyd@...omium.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

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

> 
> > 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?

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