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

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Message-ID: <CAPDyKFq6a=sj_E5Nz9bSB=6rqWq+ar2MuwcrxJAcu36N+C+m2Q@mail.gmail.com>
Date:   Mon, 15 Jan 2018 15:26:12 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.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

On 15 January 2018 at 14:22, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> Hi Rafael,
>
> On Mon, Jan 15, 2018 at 9:16 AM, Geert Uytterhoeven
> <geert@...ux-m68k.org> wrote:
>> On Mon, Jan 15, 2018 at 1:04 AM, Rafael J. Wysocki <rafael@...nel.org> wrote:
>>> On Sun, Jan 14, 2018 at 10:48 AM, Geert Uytterhoeven
>>> <geert@...ux-m68k.org> wrote:
>>>> 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...
>>>
>>> OK, thanks!
>>>
>>> It also would be good to know the topology of the device hierarchy and
>>> how that maps to the domains on the failing system (and which UART
>>> clocks are operated by genpd).
>>
>> The topology is the same on both systems.
>
> I did miss a small difference in topology: in pm/linux-next, H3 has DMA
> enabled for SCIF2, while M3 hasn't (yet).
> With DMA enabled on M3, it fails in the same way.
>
> As genpd_resume_noirq() no longer calls pm_runtime_force_resume(),
> rcar_dmac_runtime_resume() is no longer called, and the DMAC's registers
> are no longer reinitialized after system resume, breaking the serial port.

In drivers/dma/sh/rcar-dmac.c, I would try to replace the below line:
SET_SYSTEM_SLEEP_PM_OPS(rcar_dmac_sleep_suspend, rcar_dmac_sleep_resume)

with:
SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)

in case that may be too early to suspend the dma device (which is
rather common for dma devices) then try;

SET_LATE_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)

Kind regards
Uffe