linux-kernel - Re: [PATCH] PM: domains: not update genpd status when power on fail

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Message-ID: <CAPDyKFrEbwya+nHZBhTsoPSrHaebibQEuPuSL_oPKjtXcbVbhg@mail.gmail.com>
Date:   Wed, 7 Jul 2021 11:50:39 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>, Pavel Machek <pavel@....cz>,
        Len Brown <len.brown@...el.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PM: domains: not update genpd status when power on fail

On Tue, 6 Jul 2021 at 11:52, Peng Fan (OSS) <peng.fan@....nxp.com> wrote:
>
> Hi Ulf,
>
> > Subject: Re: [PATCH] PM: domains: not update genpd status when power on
> > fail
> >
> > On Tue, 6 Jul 2021 at 11:31, <peng.fan@....nxp.com> wrote:
> > >
> > > From: Peng Fan <peng.fan@....com>
> > >
> > > When _genpd_power_on fail, the generic power domain status should not
> > > be changed to GENPD_STATE_ON.
> > >
> > > Signed-off-by: Peng Fan <peng.fan@....com>
> > > ---
> > >  drivers/base/power/domain.c | 6 ++++--
> > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> > > index ab0b740cc0f1..754a5d384479 100644
> > > --- a/drivers/base/power/domain.c
> > > +++ b/drivers/base/power/domain.c
> > > @@ -1101,6 +1101,7 @@ static void genpd_sync_power_on(struct
> > generic_pm_domain *genpd, bool use_lock,
> > >                                 unsigned int depth)  {
> > >         struct gpd_link *link;
> > > +       int ret;
> > >
> > >         if (genpd_status_on(genpd))
> > >                 return;
> > > @@ -1117,8 +1118,9 @@ static void genpd_sync_power_on(struct
> > generic_pm_domain *genpd, bool use_lock,
> > >                         genpd_unlock(link->parent);
> > >         }
> > >
> > > -       _genpd_power_on(genpd, false);
> > > -       genpd->status = GENPD_STATE_ON;
> > > +       ret = _genpd_power_on(genpd, false);
> > > +       if (!ret)
> >
> > To support this error path, a lot more code needs to be added. Just
> > have a look at the callers of genpd_sync_power_on() and compare it
> > with genpd_power_on().
> >
> > In my opinion, supporting this error path isn't really worth it, at
> > least until someone comes with a valid use case. Do you have one - or
> > did you send the $subject patch based solely on code inspection?
>
> This is two patchset:
> https://patchwork.kernel.org/project/linux-arm-kernel/patch/20210604111005.6804-1-peng.fan@oss.nxp.com/
> https://patchwork.kernel.org/project/linux-arm-kernel/cover/20210629072941.7980-1-peng.fan@oss.nxp.com/
>
> I collected in github with a few fixes:
> https://github.com/MrVan/linux/tree/linux-next-master-628-blk-ctl-test

I looked at some of the changes there - and I especially don't quite
understand why you enable runtime PM for the genpd->dev. That looks
wrong to me. I am referring to:
"soc: imx: blk-ctl: fix to v8 patchset".

>
>
> In my test, when suspend/resume, I see
> pgc_vpu_h1/g1/g2 has status on, but actually they are not on in hardware.

That sounds like a bug somewhere. Did genpd fail to power off the PM
domain or what happened, more exactly?

> Because vpumix_blk_ctl bus domain is not on, pgc_vpu_h1/g1/g2 runtime
> power off will fail.

What is pgc_vpu_h1/g1/g2?

I am happy to help/guide you forward, but it sounds a bit that more
in-depth debugging is needed at your side. At least I need some stack
trace or kernel logs with debug messages enabled.

[...]

Kind regards
Uffe