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

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Message-ID: <CAMuHMdXgE3oOVdYFy3kzmOv4FXvjU4rC39gUDUtMNJCdB__2AA@mail.gmail.com>
Date:   Tue, 17 Jul 2018 09:46:23 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Viresh Kumar <viresh.kumar@...aro.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

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?

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

Can you please document these properties?
Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds