linux-kernel - Re: [PATCH 3/4] cpufreq: s5pv210: Defer probe if getting regulators fail

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Message-ID: <CAKpie0RE=F04JB+_G2K4P4d-5OLB8mvK8P0Q-+DKjwxj7aeA_w@mail.gmail.com>
Date:   Thu, 10 Jan 2019 09:03:34 +0100
From:   Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux@...linux.org.uk,
        rjw@...ysocki.net,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:SAMSUNG SOC CLOCK DRIVERS" 
        <linux-samsung-soc@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH 3/4] cpufreq: s5pv210: Defer probe if getting regulators fail

czw., 10 sty 2019 o 08:01 Viresh Kumar <viresh.kumar@...aro.org> napisał(a):
>
> On 08-01-19, 21:05, Paweł Chmiel wrote:
> > There is possibility, that when probing driver, regulators are not yet
> > initialized. In this case we should return EPROBE_DEFER and wait till
> > they're initialized, since they're required currently for cpufreq driver
> > to work. Also move regulator initialization code at beginning of probe,
> > so we can defer as fast as posibble.
> >
> > Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>
> > ---
> >  drivers/cpufreq/s5pv210-cpufreq.c | 33 +++++++++++++++++++------------
> >  1 file changed, 20 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/cpufreq/s5pv210-cpufreq.c b/drivers/cpufreq/s5pv210-cpufreq.c
> > index f51697f1e0b3..2d0e4dc7ede7 100644
> > --- a/drivers/cpufreq/s5pv210-cpufreq.c
> > +++ b/drivers/cpufreq/s5pv210-cpufreq.c
> > @@ -594,6 +594,26 @@ static int s5pv210_cpufreq_probe(struct platform_device *pdev)
> >        * this whole driver as soon as S5PV210 gets migrated to use
> >        * cpufreq-dt driver.
> >        */
> > +     arm_regulator = regulator_get(NULL, "vddarm");
> > +     if (PTR_ERR(arm_regulator) == -EPROBE_DEFER) {
> > +             pr_dbg("vddarm regulator not ready, defer\n");
> > +             return -EPROBE_DEFER;
> > +     } else if (IS_ERR(arm_regulator)) {
> > +             pr_err("failed to get regulator vddarm\n");
> > +             return PTR_ERR(arm_regulator);
> > +     }
>
> The only difference between the two cases is pr_dbg vs pr_err, its
> ugly that we have to add special code for that :(
>
> Maybe write it as:
>
>         if (IS_ERR(arm_regulator)) {
>                 if (PTR_ERR(arm_regulator) == -EPROBE_DEFER)
>                         pr_dbg...
>                 else
>                         pr_err
>                 return PTR_ERR(arm_regulator);
>         }
>
> > +
> > +     int_regulator = regulator_get(NULL, "vddint");
> > +     if (PTR_ERR(int_regulator == -EPROBE_DEFER) {
>
> Does this even compile ?
Looks like i broke it after testing (where it was working fine - was
able to change freq and gov),
and didn't catch this before sending patch for review :/.
Sorry, this (and first issue) will be fixed in v2.

Thanks for review
>
> > +             regulator_put(arm_regulator);
> > +             pr_dbg("vddint regulator not ready, defer\n");
> > +             return -EPROBE_DEFER;
> > +     } else if (IS_ERR(int_regulator)) {
> > +             regulator_put(arm_regulator);
> > +             pr_err("failed to get regulator vddint\n");
> > +             return PTR_ERR(int_regulator);
> > +     }
> > +
> >       np = of_find_compatible_node(NULL, NULL, "samsung,s5pv210-clock");
> >       if (!np) {
> >               pr_err("%s: failed to find clock controller DT node\n",
> > @@ -633,19 +653,6 @@ static int s5pv210_cpufreq_probe(struct platform_device *pdev)
> >               }
> >       }
> >
> > -     arm_regulator = regulator_get(NULL, "vddarm");
> > -     if (IS_ERR(arm_regulator)) {
> > -             pr_err("failed to get regulator vddarm\n");
> > -             return PTR_ERR(arm_regulator);
> > -     }
> > -
> > -     int_regulator = regulator_get(NULL, "vddint");
> > -     if (IS_ERR(int_regulator)) {
> > -             pr_err("failed to get regulator vddint\n");
> > -             regulator_put(arm_regulator);
> > -             return PTR_ERR(int_regulator);
> > -     }
> > -
> >       register_reboot_notifier(&s5pv210_cpufreq_reboot_notifier);
> >
> >       return cpufreq_register_driver(&s5pv210_driver);
> > --
> > 2.17.1
>
> --
> viresh