linux-kernel - Re: [PATCH v9 00/12] Support PPTT for ARM64

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Date:   Tue, 29 May 2018 14:18:40 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Jeremy Linton <jeremy.linton@....com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Mark Rutland <Mark.Rutland@....com>, austinwc@...eaurora.org,
        tnowicki@...iumnetworks.com, Palmer Dabbelt <palmer@...ive.com>,
        Will Deacon <Will.Deacon@....com>,
        linux-riscv@...ts.infradead.org, Morten.Rasmussen@....com,
        vkilari@...eaurora.org,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
        jhugo@...eaurora.org, Al Stone <ahs3@...hat.com>,
        Len Brown <lenb@...nel.org>,
        John Garry <john.garry@...wei.com>, wangxiongfeng2@...wei.com,
        Dietmar Eggemann <Dietmar.Eggemann@....com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v9 00/12] Support PPTT for ARM64



On 29/05/18 12:56, Geert Uytterhoeven wrote:
> Hi Sudeep,
> 
> On Tue, May 29, 2018 at 1:14 PM, Sudeep Holla <sudeep.holla@....com> wrote:
>> On 29/05/18 11:48, Geert Uytterhoeven wrote:
>>> On Thu, May 17, 2018 at 7:05 PM, Catalin Marinas
>>> <catalin.marinas@....com> wrote:
>>>> On Fri, May 11, 2018 at 06:57:55PM -0500, Jeremy Linton wrote:
>>>>> Jeremy Linton (12):
>>>>>   drivers: base: cacheinfo: move cache_setup_of_node()
>>>>>   drivers: base: cacheinfo: setup DT cache properties early
>>>>>   cacheinfo: rename of_node to fw_token
>>>>>   arm64/acpi: Create arch specific cpu to acpi id helper
>>>>>   ACPI/PPTT: Add Processor Properties Topology Table parsing
>>>>>   ACPI: Enable PPTT support on ARM64
>>>>>   drivers: base cacheinfo: Add support for ACPI based firmware tables
>>>>>   arm64: Add support for ACPI based firmware tables
>>>>>   arm64: topology: rename cluster_id
>>>>>   arm64: topology: enable ACPI/PPTT based CPU topology
>>>>>   ACPI: Add PPTT to injectable table list
>>>>>   arm64: topology: divorce MC scheduling domain from core_siblings
>>>>
>>>> Queued for 4.18 (without Sudeep's latest property_read_u64 cacheinfo
>>>> patch - http://lkml.kernel.org/r/20180517154701.GA20281@e107155-lin; I
>>>> can add it separately).
>>>
>>> This is now commit 37c3ec2d810f87ea ("arm64: topology: divorce MC
>>> scheduling domain from core_siblings") in arm64/for-next/core, causing
>>> system suspend on big.LITTLE systems to hang after shutting down the first
>>> CPU:
>>>
>>>     $ echo mem > /sys/power/state
>>>     PM: suspend entry (deep)
>>>     PM: Syncing filesystems ... done.
>>>     Freezing user space processes ... (elapsed 0.001 seconds) done.
>>>     OOM killer disabled.
>>>     Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
>>>     Disabling non-boot CPUs ...
>>>     CPU1: shutdown
>>>     psci: CPU1 killed.
>>>
>>
>> Is it OK to assume the suspend failed just after shutting down one CPU
>> or it's failing during resume ? It depends on whether you had console
>> disabled or not.
> 
> I have no-console-suspend enabled.
> It's failing during suspend, the next lines should be:
> 
>     CPU2: shutdown
>     psci: CPU2 killed.
>     ...
> 

OK, I was hoping to be something during resume as this patch has nothing
executed during suspend. Do you see any change in topology before and
after this patch applied. I am interested in the output of:

$ grep "" /sys/devices/system/cpu/cpu*/topology/*

>>> For me, it fails on the following big.LITTLE systems:
>>>
>>>     R-Car H3 ES2.0 (4xCA57 + 4xCA53)
>>>     R-Car M3-W (2xCA57 + 4xCA53)
>>>
>>
>> Interesting, is it PSCI based system suspend ?
> 
> Yes it is.
> 
> Suspend-to-idle, which doesn't offline CPUs, still works.
> 

>From DT, I guess this platform doesn't have any idle states.
Does this use genpd power domains ? I see power-domains in the DT, so
asking to get more info. Do you have any out of tree patches especially
if they are depending on some topology cpumasks ?

>>> System supend still works fine on systems with big cores only:
>>>
>>>     R-Car H3 ES1.0 (4xCA57 (4xCA53 disabled in firmware))
>>>     R-Car M3-N (2xCA57)
>>>
>>> Reverting this commit fixes the issue for me.
>>
>> I can't find anything that relates to system suspend in these patches
>> unless they are messing with something during CPU hot plug-in back
>> during resume.
> 
> It's only the last patch that introduces the breakage.
> 

As specified in the commit log, it won't change any behavior for DT
systems if it's non-NUMA or single node system. So I am still wondering
what could trigger this regression.

-- 
Regards,
Sudeep