linux-kernel - Re: [PATCH] Revert "cpuidle: Make drivers initialize polling state"

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Date:   Tue, 06 Feb 2018 19:00:12 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [PATCH] Revert "cpuidle: Make drivers initialize polling state"

On Tuesday, February 6, 2018 5:31:34 PM CET Ville Syrjälä wrote:
> On Mon, Feb 05, 2018 at 06:56:31PM +0100, Rafael J. Wysocki wrote:
> > On Monday, February 5, 2018 3:04:45 PM CET Ville Syrjälä wrote:
> > > On Sun, Feb 04, 2018 at 10:18:07AM +0100, Rafael J. Wysocki wrote:
> > > > On Sun, Feb 4, 2018 at 10:12 AM, Rafael J. Wysocki <rafael@...nel.org> wrote:
> > > > > On Mon, Jan 22, 2018 at 5:27 PM, Ville Syrjala
> > > > > <ville.syrjala@...ux.intel.com> wrote:
> > > > >> From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> > > > >>
> > > > >> This reverts commit 1b39e3f813b4685c7a30ae964d5529a1b0e3a286.
> > > > >>
> > > > >> Makes my P3 machine oops somewhere in cpuidle. I suspect
> > > > >> CONFIG_ACPI=n may have something to do with this.
> > > > >
> > > > > And if you don't do CONFIG_ACPI=n, does it still oops?
> > > 
> > > Don't think I actually tried that. I can give it a whirl tonight.
> > > 
> > > I think this machine should actually have ACPI, but it inherited
> > > the .config from a P2 machine that did not. Apparently I was too
> > > lazy to change .config when I swapped in the "new" machine.
> > 
> > I guess it would work, but never mind.
> > 
> > > > >
> > > > > Anyway, there are later changes depending on this one, so reverting it
> > > > > won't work in general.
> > > > >
> > > > > Let me look deeper at this.
> > > > 
> > > > What's there in /sys/devices/system/cpu/cpuidle/current_driver on your
> > > > system with the problematic commit reverted?
> > > 
> > > # cat /sys/devices/system/cpu/cpuidle/current_driver
> > > apm_idle
> > 
> > That is the key bit: I overlooked this little fellow.
> > 
> > Does the below (untested here) help?
> > 
> > ---
> >  arch/x86/kernel/apm_32.c |    1 +
> >  1 file changed, 1 insertion(+)
> > 
> > Index: linux-pm/arch/x86/kernel/apm_32.c
> > ===================================================================
> > --- linux-pm.orig/arch/x86/kernel/apm_32.c
> > +++ linux-pm/arch/x86/kernel/apm_32.c
> > @@ -2389,6 +2389,7 @@ static int __init apm_init(void)
> >  	if (HZ != 100)
> >  		idle_period = (idle_period * HZ) / 100;
> >  	if (idle_threshold < 100) {
> > +		cpuidle_poll_state_init(&apm_idle_driver);
> >  		if (!cpuidle_register_driver(&apm_idle_driver))
> >  			if (cpuidle_register_device(&apm_cpuidle_device))
> >  				cpuidle_unregister_driver(&apm_idle_driver);
> 
> Yep, this works. Thanks.
> 
> Tested-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>

Thanks!

Let me respin it with a changelog/tags etc