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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Wed, 6 Oct 2021 14:43:41 +0200
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Subject: Re: [PATCH v13 06/35] clk: tegra: Support runtime PM and power domain
To:     Dmitry Osipenko <digetx@gmail.com>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Viresh Kumar <vireshk@kernel.org>,
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On Wed, 6 Oct 2021 at 00:43, Dmitry Osipenko <digetx@gmail.com> wrote:
>
> 06.10.2021 01:19, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> ...
> > I reproduced the OFF problem by removing the clk prepare/unprepare from
> > the suspend/resume of the clk driver and making some extra changes to
> > clock tree topology and etc to trigger the problem on Nexus 7.
> >
> > tegra-pmc 7000e400.pmc: failed to turn off PM domain heg: -13
> >
> > It happens from genpd_suspend_noirq() -> tegra_genpd_power_off() -> clk
> > -> GENPD -> I2C -> runtime-pm.
> >
> > -13 is EACCES, it comes from the runtime PM of I2C device. RPM is
> > prohibited/disabled during late (NOIRQ) suspend by the drivers core.
>
> My bad, I double-checked and it's not I2C RPM that is failing now, but
> the clock's RPM [1], which is also unavailable during NOIRQ.

Yes, that sounds reasonable.

You would then need a similar patch for the tegra clock driver as I
suggested for tegra I2C driver. That should solve the problem, I
think.

>
> [1]
> https://elixir.free-electrons.com/linux/v5.15-rc4/source/drivers/clk/clk.=
c#L116
>
> Previously it was I2C RPM that was failing in a similar way, but code
> changed a tad since that time.

Alright. In any case, as long as the devices gets suspended in the
correct order, I think it should be fine to cook a patch along the
lines of what I suggest for the I2C driver as well.

It should work, I think. Although, maybe you want to avoid runtime
resuming the I2C device, unless it's the device belonging to the PMIC
interface, if there is a way to distinguish that for the driver.

Kind regards
Uffe