linux-kernel - Re: [PATCH 0/2] PM / core: genpd fix and pm_runtime_force

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Message-ID: <CAMuHMdVaiuscrvat=BqtmXxQnA35=wocb85FHEFvQWjQaY615g@mail.gmail.com>
Date:   Sun, 14 Jan 2018 10:48:18 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH 0/2] PM / core: genpd fix and pm_runtime_force_suspend|resume()
 rework

Hi Rafael,

On Sat, Jan 13, 2018 at 1:38 AM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> On Friday, January 12, 2018 3:31:09 PM CET Geert Uytterhoeven wrote:
>> On Fri, Jan 12, 2018 at 2:00 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
>> > This comes from the recent discussion/testing effort that ensued after my
>> > pm_runtime_force_suspend|resume() changes proposal:
>> >
>> > https://marc.info/?t=151497772000004&r=1&w=2
>> >
>> > Patch [1/2] basically is https://patchwork.kernel.org/patch/10152873/ rebased
>> > on top of the current linux-next branch of the linux-pm.git tree (the relevant
>> > part should be there in the linux-next tree proper ATM).  It applies on top
>> > of https://patchwork.kernel.org/patch/10156077/ which should apply to the Linus'
>> > tree cleanly.
>> >
>> > Patch [2/2] is a resend of https://patchwork.kernel.org/patch/10142047/ with
>> > a very minor changelog modification and the R-b tag from Ulf.
>> >
>> > Geert, if possible, please test this on the Renesas systems that had the
>> > problem with https://patchwork.kernel.org/patch/10142047/ previously and let
>> > me know if you still see issues.
>>
>> I've tested this on two very similar systems: Salvator-XS with R-Car H3 ES2.0,
>> and Salvator-X with R-Car M3-W ES1.0.
>>
>> On the M3-based system, everything seems to work fine.
>
> Good.
>
>> On the H3-based system, the serial console (the /dev/ttySC0 device, not kernel
>> serial output) is dead after resume from s2ram, with and without
>> no_console_suspend.
>>
>> With no_console_suspend, I see:
>>
>>     ttySC ttySC0: 1 input overrun(s)
>>
>> after typing on the serial console, so it looks like an interrupt problem.
>>
>> This issue seems to be caused by patch [1/2]. But I have no idea what's
>> really happening, and why the two systems behave differently.

Could be a firmware issue, too.
While the kernel images are identical, the ARM trusted firmware configs aren't
(same version, though).

I'll do some more investigation...

> Well, that's not dramatic.
>
> Let's make a deal that we'll fix this on top of [1/2].

;-)

> Which driver is this BTW?  sh-sci?  That one doesn't even support runtime
> PM, confusingly enough.

Yes, sh-sci. It does make pm_runtime_*() calls.
And of course there's uart_ops.pm, which is driven from serial_core...

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds