linux-kernel - Re: [PATCH v3 2/2] soc: qcom: rpmh-rsc: Timeout after 1 second in write_tcs_reg

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Date:   Thu, 28 May 2020 07:51:03 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Maulik Shah <mkshah@...eaurora.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Joe Perches <joe@...ches.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Evan Green <evgreen@...omium.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] soc: qcom: rpmh-rsc: Timeout after 1 second in write_tcs_reg_sync()

Hi,

On Thu, May 28, 2020 at 4:44 AM Maulik Shah <mkshah@...eaurora.org> wrote:
>
> Hi Doug,
>
> During suspend-resume with this change on sc7180 using latest
> linux-next, below warning was reported.
>
> WARNING: CPU: 0 PID: 5324 at kernel/time/timekeeping.c:754
> ktime_get+0x94/0x9c
>   ktime_get+0x94/0x9c
>   write_tcs_reg_sync+0x4c/0x130
>   tcs_invalidate+0x64/0xa4
>   rpmh_rsc_invalidate+0x20/0x38
>   rpmh_flush+0x58/0x1ec
>   rpmh_rsc_cpu_pm_callback+0xe4/0x144
>   notifier_call_chain+0x58/0x90
>   __atomic_notifier_call_chain+0x48/
>   cpu_pm_notify+0x40/0x6c
>   cpu_pm_enter+0x34/0x7c
>   cpu_pm_suspend+0x10/0x20
>   syscore_suspend+0x128/0x2a4
>   suspend_devices_and_enter+0x5e0/0x8a0
>
> This seems to be because timekeeping is already suspend by this time.

Thanks for the report.  I posted:

https://lore.kernel.org/r/20200528074530.1.Ib86e5b406fe7d16575ae1bb276d650faa144b63c@changeid

I think there are still a bunch of not-yet-landed patches needed for
suspend-resume so I only confirmed that the code still works OK for
the idle case.  Hopefully you can confirm s2r is good, though I'd
believe it should be exactly the same.  I'm 99% sure that udelay()
still works fine even when timekeeping is suspended.

-Doug