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Date:   Tue, 14 Jul 2020 18:10:21 +0200
From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     Zhang Rui <rui.zhang@intel.com>,
        Robert Moore <robert.moore@intel.com>,
        Erik Kaneda <erik.kaneda@intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@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>,
        Stephen Berman <stephen.berman@gmx.net>,
        "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" <devel@acpica.org>
Subject: Re: power-off delay/hang due to commit 6d25be57 (mainline)
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On 2020-07-14 17:53:15 [+0200], Rafael J. Wysocki wrote:
> > shows the pattern and we nailed it down that it comes from
> > thermal_get_temp().
> 
> acpi_evaluate_integer() doesn't show up in the trace, though, AFAICS.

I deducted it. acpi_thermal_get_temperature() -> acpi_evaluate_integer()
and the dmesg showed
| ACPI: Invalid passive threshold
| thermal LNXTHERM:00: registered as thermal_zone0
| ACPI: Thermal Zone [TZ10] (17 C)
| thermal LNXTHERM:01: registered as thermal_zone1
| ACPI: Thermal Zone [TZ00] (28 C)

and overriding thermal.tzp to a higher value made the issue go away.
There is a complete dmesg
     https://lore.kernel.org/lkml/87v9l65d2y.fsf@gmx.net/

> > I assumed acpi_ex_opcode_2A_0T_0R() since the other
> > candidate was acpi_ev_asynch_execute_gpe_method().
> 
> Which probably is the case.  Specifically
> 
> acpi_ev_asynch_execute_gpe_method: Evaluate _L66
> 
> is likely to cause the Notify() to be dispatched.

Okay. I hope Stephen replies later with a backtrace.

> > Stephen, the patch attached adds a WARN_ON() statement which will
> > produce a stack trace (4 or so). Could please run 'dmesg' after a while
> > and send it back. There should be a
> >     "WARNING in drivers/acpi/acpica/evmisc.c"
> >
> > statement or something along the lines.
> >
> > Rafael, are you also interested in an ACPI dump?
> 
> That might help a bit.
> 
> So what probably happens is that poking at the TZ causes a GPE to
> trigger and a Notify() to be dispatched which then goes into the
> workqueue for execution.
> 
> Now, I'm not sure what happens to those Notify() items, though.  They
> each should cause a handler (in the thermal driver) to be executed,
> but does that happen?

Are you asking for a trace point in acpi_ev_notify_dispatch() to see
what it actually calls as in info->notify.global->handler /
handler_obj->notify.handler ?
There is no handler in the thermal driver or do I just not recognize it?

Sebastian