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From:   Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
To:     Marco Felsch <m.felsch@pengutronix.de>,
        Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
CC:     Support Opensource <Support.Opensource@diasemi.com>,
        "lee.jones@linaro.org" <lee.jones@linaro.org>,
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        "lgirdwood@gmail.com" <lgirdwood@gmail.com>,
        "broonie@kernel.org" <broonie@kernel.org>,
        Steve Twiss <stwiss.opensource@diasemi.com>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 2/5] dt-bindings: mfd: da9062: add regulator voltage
 selection documentation
Thread-Topic: [PATCH 2/5] dt-bindings: mfd: da9062: add regulator voltage
 selection documentation
Thread-Index: AQHVbVV1957uISHJUEeJggkt0eobi6c6l9DggAH/z4CAAAcsgIABChoAgAAjQKA=
Date:   Thu, 26 Sep 2019 10:17:06 +0000
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References: <20190917124246.11732-1-m.felsch@pengutronix.de>
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In-Reply-To: <20190926080956.a3k2z4gf3n6m3n4s@pengutronix.de>
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On 26 September 2019 09:10, Marco Felsch wrote:

> On 19-09-25 16:18, Adam Thomson wrote:
> > On 25 September 2019 16:52, Marco Felsch wrote:
> >
> > > Hi Adam,
> > >
> > > On 19-09-24 09:23, Adam Thomson wrote:
> > > > On 17 September 2019 13:43, Marco Felsch wrote:
> > > >
> > > > > Add the documentation which describe the voltage selection gpio
> support.
> > > > > This property can be applied to each subnode within the 'regulato=
rs'
> > > > > node so each regulator can be configured differently.
> > > > >
> > > > > Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> > > > > ---
> > > > >  Documentation/devicetree/bindings/mfd/da9062.txt | 9 +++++++++
> > > > >  1 file changed, 9 insertions(+)
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/mfd/da9062.txt
> > > > > b/Documentation/devicetree/bindings/mfd/da9062.txt
> > > > > index edca653a5777..9d9820d8177d 100644
> > > > > --- a/Documentation/devicetree/bindings/mfd/da9062.txt
> > > > > +++ b/Documentation/devicetree/bindings/mfd/da9062.txt
> > > > > @@ -66,6 +66,15 @@ Sub-nodes:
> > > > >    details of individual regulator device can be found in:
> > > > >    Documentation/devicetree/bindings/regulator/regulator.txt
> > > > >
> > > > > +  Optional regulator device-specific properties:
> > > > > +  - dlg,vsel-sense-gpios : The GPIO reference which should be us=
ed by
> the
> > > > > +    regulator to switch the voltage between active/suspend volta=
ge
> settings.
> > > If
> > > > > +    the signal is active the active-settings are applied else th=
e suspend
> > > > > +    settings are applied. Attention: Sharing the same gpio for o=
ther
> purposes
> > > > > +    or across multiple regulators is possible but the gpio setti=
ngs must be
> the
> > > > > +    same. Also the gpio phandle must refer to to the dlg,da9062-=
gpio
> device
> > > > > +    other gpios are not allowed and make no sense.
> > > > > +
> > > >
> > > > Should we not use the binding names that are defined in 'gpio-
> regulator.yaml'
> > > as
> > > > these seem to be generic and would probably serve the purpose here?
> > >
> > > Hm.. as the description says:
> > >
> > > 8<--------------------------------------------------
> > > gpios:
> > >    description: Array of one or more GPIO pins used to select the
> > >    regulator voltage/current listed in "states".
> > > 8<--------------------------------------------------
> > >
> > > But we don't have a "states" property and we can't select between
> > > voltage or current.
> >
> > Yes I think I was at cross purposes when I made this remark. The bindin=
gs there
> > describe the GPOs that are used to enable/disable and set voltage/curre=
nt for
> > regulators and the supported voltage/current levels that can be configu=
red in
> > this manner. What you're describing is the GPI for DA9061/2. If you loo=
k at
> > GPIO handling in existing regulator drivers I believe they all deal wit=
h external
> > GPOs that are configured to enable/disable and set voltage/current limi=
ts
> rather
> > than the GPI on the PMIC itself. That's why I'm thinking that the confi=
gurations
> > you're doing here should actually be in a pinctrl or GPIO driver.
>=20
> That's true, the common gpio bindings are from the view of the
> processor, e.g. which gpio must the processor drive to enable/switch the
> regualtor. So one reasone more to use a non-common binding.
>=20
> Please take a look on my other comment I made :) I don't use the
> gpio-alternative function. I use it as an input.

I know in the datasheet this isn't marked as an alternate function specific=
ally
but to me having regulator control by the chip's own GPI is an alternative
function for that GPIO pin, in the same way a specific pin can be used for
SYS_EN or Watchdog control. It's a dedicated purpose rather than being a no=
rmal
GPI.

See the following as an example of what I'm suggesting:

https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bin=
dings/pinctrl/pinctrl-palmas.txt

You could then pass the pinctrl information to the regulator driver and use
that rather than having device specific bindings for this. That's at least =
my
current interpretation of this anyway.

>=20
> Regards,
>   Marco
>=20
>=20
> > I'd be interested in hearing Mark's view on this though as he has far m=
ore
> > experience in this area than I do.
> >
> > >
> > > Regards,
> > >   Marco
> > >
> > > > >  - rtc : This node defines settings required for the Real-Time Cl=
ock
> associated
> > > > >    with the DA9062. There are currently no entries in this bindin=
g, however
> > > > >    compatible =3D "dlg,da9062-rtc" should be added if a node is c=
reated.
> > > > > --
> > > > > 2.20.1
> > > >
> > > >
> > >
> > > --
> > > Pengutronix e.K.                           |                         =
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> >
>=20
> --
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