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From:   Stephen Berman <stephen.berman@gmx.net>
To:     "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Zhang Rui <rui.zhang@intel.com>,
        Robert Moore <robert.moore@intel.com>,
        Erik Kaneda <erik.kaneda@intel.com>,
        Len Brown <lenb@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" <devel@acpica.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: power-off delay/hang due to commit 6d25be57 (mainline)
References: <87blkbx1gt.fsf@gmx.net>
        <CAJZ5v0j86pX_a4bSLP=sobLoYhfQYV9dWL8HHf2941kXgND79g@mail.gmail.com>
        <CAJZ5v0j7i86twMS+csYMaetUkvqjof4FD2GRNoZ_AN=SBF7F1w@mail.gmail.com>
        <9709109.MH8tSaV5v9@kreacher> <87eej0iuf0.fsf@gmx.net>
Date:   Sun, 24 Jan 2021 14:49:03 +0100
In-Reply-To: <87eej0iuf0.fsf@gmx.net> (Stephen Berman's message of "Mon, 04
        Jan 2021 16:38:43 +0100")
Message-ID: <87wnw278ds.fsf@gmx.net>
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On Mon, 04 Jan 2021 16:38:43 +0100 Stephen Berman <stephen.berman@gmx.net> wrote:

> On Thu, 31 Dec 2020 21:46:11 +0100 "Rafael J. Wysocki" <rjw@rjwysocki.net> wrote:
>
>> ATM, I'm tempted to do something like the patch below (with the rationale
>> that it shouldn't be necessary to read the temperature right after updating
>> the trip points if polling is in use, because the next update through polling
>> will cause it to be read anyway and it will trigger trip point actions as
>> needed).
>>
>> Stephen, can you give it a go, please?
>
> On Sat, 02 Jan 2021 12:03:17 +0100 "Rafael J. Wysocki" <rjw@rjwysocki.net> wrote:
>
>> There is one more way to address this, probably better: instead of checking the
>> temperature right away in acpi_thermal_notify(), queue that on
>> acpi_thermal_pm_queue
>> and so only if another thermal check is not pending.
>>
>> This way there will be at most one temperature check coming from
>> acpi_thermal_notify() queued up at any time which should prevent the
>> build-up of work items from taking place.
>>
>> So something like this:
>
> Thanks for the patches.  I'll try them as soon as I can.

FTR, since this is the thread I started for this bug, I've confirmed in
https://lore.kernel.org/lkml/87y2gi78sg.fsf@gmx.net/T/#t that the latest
patch fixes the bug.

Steve Berman