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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Wed, 2 Dec 2020 20:13:38 +0100
Message-ID: <CAJZ5v0j7i86twMS+csYMaetUkvqjof4FD2GRNoZ_AN=SBF7F1w@mail.gmail.com>
Subject: Re: power-off delay/hang due to commit 6d25be57 (mainline)
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Stephen Berman <stephen.berman@gmx.net>,
        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>
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On Wed, Dec 2, 2020 at 7:31 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Wed, Dec 2, 2020 at 7:03 PM Sebastian Andrzej Siewior
> <bigeasy@linutronix.de> wrote:
> >
> > On 2020-10-26 18:20:59 [+0100], To Rafael J. Wysocki wrote:
> > > > > > > Done as Bug 208877.
> > > > > Rafael, do you have any suggestions?
> > > >
> > > > I've lost track of this sorry.
> > > >
> > > > I have ideas, let me get back to this next week.
> > >
> > > :)
> >
> > Rafael, any update? If you outline an idea or so then I may be able to
> > form a patch out of it. Otherwise I have no idea how to fix this - other
> > than telling the driver to not poll in smaller intervals than
> > 30secs.
>
> The idea, roughly speaking, is to limit the number of outstanding work
> items in the queue (basically, if there's a notification occurring
> before the previous one can be handled, there is no need to queue up
> another work item for it).

That's easier said than done, though, because of the way the work item
queue-up is hooked up into the ACPICA code.