linux-kernel - Re: [PATCH v2] soc: mediatek: Check if power domains can be powered on at boot time

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Date:   Mon, 5 Oct 2020 09:08:16 +0800
From:   Nicolas Boichat <drinkcat@...omium.org>
To:     Matthias Brugger <matthias.bgg@...il.com>
Cc:     Daniel Kurtz <djkurtz@...omium.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v2] soc: mediatek: Check if power domains can be powered
 on at boot time

On Thu, Oct 1, 2020 at 11:03 PM Matthias Brugger <matthias.bgg@...il.com> wrote:
>
>
>
> On 28/09/2020 05:31, Nicolas Boichat wrote:
> > In the error case, where a power domain cannot be powered on
> > successfully at boot time (in mtk_register_power_domains),
> > pm_genpd_init would still be called with is_off=false, and the
> > system would later try to disable the power domain again, triggering
> > warnings as disabled clocks are disabled again (and other potential
> > issues).
> >
> > Also print a warning splat in that case, as this should never
> > happen.
> >
> > Fixes: c84e358718a66f7 ("soc: Mediatek: Add SCPSYS power domain driver")
> > Signed-off-by: Nicolas Boichat <drinkcat@...omium.org>
>
> Applied to v5.10-tmp/soc which will be v5.10-next/soc as soon as v5.10-rc1 gets
> published.
>
> Nicolas can you please make sure that similar logic will be part of the series
> Enric is working on?

https://patchwork.kernel.org/patch/11811767/ the logic is a bit
different, and the whole scpsys driver would fail to probe, but I
think that's also reasonable behaviour.

Thanks,

>
> Thanks a lot.
> Matthias
>
> > ---
> >
> > Changes in v2:
> >   - Add WARN_ON if the domain can't be powered on, to make it more
> >     obvious that this should not happen (there is already an error
> >     message).
> >
> >   drivers/soc/mediatek/mtk-scpsys.c | 5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
> > index f669d3754627..ca75b14931ec 100644
> > --- a/drivers/soc/mediatek/mtk-scpsys.c
> > +++ b/drivers/soc/mediatek/mtk-scpsys.c
> > @@ -524,6 +524,7 @@ static void mtk_register_power_domains(struct platform_device *pdev,
> >       for (i = 0; i < num; i++) {
> >               struct scp_domain *scpd = &scp->domains[i];
> >               struct generic_pm_domain *genpd = &scpd->genpd;
> > +             bool on;
> >
> >               /*
> >                * Initially turn on all domains to make the domains usable
> > @@ -531,9 +532,9 @@ static void mtk_register_power_domains(struct platform_device *pdev,
> >                * software.  The unused domains will be switched off during
> >                * late_init time.
> >                */
> > -             genpd->power_on(genpd);
> > +             on = !WARN_ON(genpd->power_on(genpd) < 0);
> >
> > -             pm_genpd_init(genpd, NULL, false);
> > +             pm_genpd_init(genpd, NULL, !on);
> >       }
> >
> >       /*
> >