linux-kernel - Re: [PATCH] drivers/acpi: Clear status of an event before enabling it

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Message-ID: <CAEGmHFHvOJWOjgEz3mYBKGeb4+r_QfuLaWb=NW8mq7GTXdefVA@mail.gmail.com>
Date:   Thu, 28 Mar 2019 16:48:24 -0700
From:   Furquan Shaikh <furquan@...gle.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Robert Moore <robert.moore@...el.com>,
        "Schmauss, Erik" <erik.schmauss@...el.com>,
        Rafael Wysocki <rafael.j.wysocki@...el.com>,
        Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        devel@...ica.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Rajat Jain <rajatja@...gle.com>,
        Evan Green <evgreen@...gle.com>,
        Duncan Laurie <dlaurie@...gle.com>
Subject: Re: [PATCH] drivers/acpi: Clear status of an event before enabling it

On Thu, Mar 28, 2019 at 1:57 AM Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> On Thu, Mar 28, 2019 at 1:46 AM Furquan Shaikh <furquan@...gle.com> wrote:
> >
> > On Wed, Mar 27, 2019 at 5:24 AM Rafael J. Wysocki <rafael@...nel.org> wrote:
> > >
> > > On Thu, Mar 21, 2019 at 3:16 AM Furquan Shaikh <furquan@...gle.com> wrote:
> > > >
> > > > On Wed, Mar 20, 2019 at 5:11 PM Rafael J. Wysocki <rafael@...nel.org> wrote:
> > > > >
> > > > > On Wed, Mar 20, 2019 at 11:34 PM Furquan Shaikh <furquan@...gle.com> wrote:
> > > > > >
> > > > > > Commit 18996f2db918 ("ACPICA: Events: Stop unconditionally
> > > > > > clearing ACPI IRQs during suspend/resume") was added to stop clearing
> > > > > > of event status bits unconditionally on suspend and resume paths. This
> > > > > > was done because of an issue
> > > > > > reported (https://bugzilla.kernel.org/show_bug.cgi?id=196249) where
> > > > > > lid status stays closed even on resume (which happens because event
> > > > > > status bits are cleared unconditionally on resume). Though this change
> > > > > > fixed the issue on suspend path, it introduced regressions on several
> > > > > > resume paths.
> > > > > >
> > > > > > First regression was reported and fixed on S5 path by the following
> > > > > > change: commit fa85015c0d95 ("ACPICA: Clear status of all events when
> > > > > > entering S5"). Next regression was reported and fixed on all legacy
> > > > > > sleep paths by the commit f317c7dc12b7 ("ACPICA: Clear status of all
> > > > > > events when entering sleep states"). However, regression still exists
> > > > > > on S0ix sleep path since it does not follow the legacy sleep path.
> > > > >
> > > > > What exactly is failing?
> > > >
> > > > Here is the failure scenario:
> > > >
> > > > 1. Consider the case of trackpad which acts as a wake source.
> > > > 2. Since the pad is configured for SCI, GPE_STS gets set for that pad
> > > > during normal interrupts as well (i.e. during probe at boot or when
> > > > using the trackpad)
> > >
> > > I don't quite understand this.
> > >
> > > Is the same GPE used for signaling trackpad events in the system
> > > working state and for wakeup?
> >
> > Yes. The same pad is being configured for interrupts (i.e. routed to
> > APIC) during S0 as well as configured for GPE (i.e. routed for SCI) to
> > cause wakes when in S0ix/S3. This pad is externally connected to
> > trackpad interrupt line.
>
> And the way the system is wired up causes the GPE status to be set
> when it is enabled, I suppose?

That is correct.

>
> So effectively, you need to disable the active-state IRQ, then clear
> the GPE status and enable it for wakeup.
>
> OK, I'll queue up the patch (and talk to the upstream ACPICA people
> about taking it in there).

Thank you!

>
> Thanks!