linux-kernel - Re: [PATCH V3 11/16] cpufreq: dt: Pass regulator name to the OPP core

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Message-ID: <20180718055029.rdo427kozpwqm2bc@vireshk-i7>
Date:   Wed, 18 Jul 2018 11:20:29 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linaro-kernel <linaro-kernel@...ts.linaro.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Nishanth Menon <nm@...com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH V3 11/16] cpufreq: dt: Pass regulator name to the OPP core

On 17-07-18, 09:46, Geert Uytterhoeven wrote:
> Hi Viresh,
> 
> CC device-tree folks
> 
> Replying to an old email, because that's the most accurate reference I
> could find.
> 
> On Tue, Feb 9, 2016 at 6:06 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
> > OPP core can handle the regulators by itself, and but it needs to know
> > the name of the regulator to fetch. Add support for that.
> >
> > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> > ---
> >  drivers/cpufreq/cpufreq-dt.c | 46 ++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 46 insertions(+)
> >
> > diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
> > index 4c9f8a828f6f..2af75f8088bb 100644
> > --- a/drivers/cpufreq/cpufreq-dt.c
> > +++ b/drivers/cpufreq/cpufreq-dt.c
> 
> > @@ -119,6 +120,30 @@ static int set_target(struct cpufreq_policy *policy, unsigned int index)
> >         return ret;
> >  }
> >
> > +/*
> > + * An earlier version of opp-v1 bindings used to name the regulator
> > + * "cpu0-supply", we still need to handle that for backwards compatibility.
> > + */
> > +static const char *find_supply_name(struct device *dev, struct device_node *np)
> > +{
> > +       struct property *pp;
> > +       int cpu = dev->id;
> > +
> > +       /* Try "cpu0" for older DTs */
> > +       if (!cpu) {
> > +               pp = of_find_property(np, "cpu0-supply", NULL);
> > +               if (pp)
> > +                       return "cpu0";
> > +       }
> > +
> > +       pp = of_find_property(np, "cpu-supply", NULL);
> > +       if (pp)
> > +               return "cpu";
> 
> Despite the existence of lots of users of these properties, I couldn't find
> both the "earlier version" and the "current version" of the opp-v1 bindings
> documenting the "cpu0-supply" and "cpu-supply" properties?

They are part of the device nodes and don't fall under the
jurisdiction of OPP tables and so aren't defined there. We rely on the
"<name>-supply" property from the regulator bindings for the devices.

> Even for opp-v2, they are not documented in
> Documentation/devicetree/bindings/opp/opp.txt, but cpu-supply is used in
> the examples?

Same reasoning here as well.

> For v2, I did find "[PATCH 01/16] PM / OPP: Add 'supply-names' binding"
> https://lore.kernel.org/lkml/2b87b162eabd1570ae2311e1ef8655acda72f678.1441972771.git.viresh.kumar@linaro.org/
> but presumably that's an even further evolution?

Yeah, that never made it to mainline is abandoned.

> Can you please document these properties?

I don't think we need to, do we ?

-- 
viresh