linux-kernel - Re: [PATCH 2/5] dt-bindings: mfd: da9062: add regulator voltage selection documentation

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Date:   Thu, 26 Sep 2019 10:09:56 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Cc:     Support Opensource <Support.Opensource@...semi.com>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        Steve Twiss <stwiss.opensource@...semi.com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] dt-bindings: mfd: da9062: add regulator voltage
 selection documentation

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 'regulators'
> > > > node so each regulator can be configured differently.
> > > >
> > > > Signed-off-by: Marco Felsch <m.felsch@...gutronix.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 used by the
> > > > +    regulator to switch the voltage between active/suspend voltage settings.
> > If
> > > > +    the signal is active the active-settings are applied else the suspend
> > > > +    settings are applied. Attention: Sharing the same gpio for other purposes
> > > > +    or across multiple regulators is possible but the gpio settings 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 bindings there
> describe the GPOs that are used to enable/disable and set voltage/current for
> regulators and the supported voltage/current levels that can be configured in
> this manner. What you're describing is the GPI for DA9061/2. If you look at
> GPIO handling in existing regulator drivers I believe they all deal with external
> GPOs that are configured to enable/disable and set voltage/current limits rather
> than the GPI on the PMIC itself. That's why I'm thinking that the configurations
> you're doing here should actually be in a pinctrl or GPIO driver.

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.

Please take a look on my other comment I made :) I don't use the
gpio-alternative function. I use it as an input.

Regards,
  Marco


> I'd be interested in hearing Mark's view on this though as he has far more
> experience in this area than I do.
> 
> > 
> > Regards,
> >   Marco
> > 
> > > >  - rtc : This node defines settings required for the Real-Time Clock associated
> > > >    with the DA9062. There are currently no entries in this binding, however
> > > >    compatible = "dlg,da9062-rtc" should be added if a node is created.
> > > > --
> > > > 2.20.1
> > >
> > >
> > 
> > --
> > Pengutronix e.K.                           |                             |
> > Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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> 

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |