linux-kernel - Re: [PATCH v3] platform/x86:intel/pmc: Enable the ACPI PM Timer to be turned off when suspended

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Message-ID: <CAGcaFA2eXzzCVqG-DSWDb1gruV4FemRC3W+dgRub7GgcOyf7yQ@mail.gmail.com>
Date: Wed, 31 Jul 2024 23:41:42 +0200
From: Marek Maślanka <mmaslanka@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>, 
	Rajneesh Bhardwaj <irenic.rajneesh@...il.com>, David E Box <david.e.box@...el.com>, 
	Hans de Goede <hdegoede@...hat.com>, Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
	John Stultz <jstultz@...gle.com>, Stephen Boyd <sboyd@...nel.org>, 
	platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v3] platform/x86:intel/pmc: Enable the ACPI PM Timer to be
 turned off when suspended

On Wed, Jul 31, 2024 at 6:33 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> Marek!
>
> On Wed, Jul 31 2024 at 16:44, Marek Maślanka wrote:
> > On Tue, Jul 30, 2024 at 6:08 PM Thomas Gleixner <tglx@...utronix.de> wrote:
> >> On Tue, Jul 30 2024 at 12:05, Marek Maslanka wrote:
> >> +static void acpi_pm_disable(struct clocksource *cs)
> >> +{
> >> +       acpi_pm_enabled = false;
> >> +       if (enable_callback)
> >> +               enable_callback(false);
> >> +}
> >> +
> >>  static struct clocksource clocksource_acpi_pm = {
> >>         .name           = "acpi_pm",
> >>         .rating         = 200,
> >>         .read           = acpi_pm_read,
> >>         .mask           = (u64)ACPI_PM_MASK,
> >>         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
> >> +       .enable         = acpi_pm_enable,
> >> +       .disable        = acpi_pm_disable,
> >>  };
> >>
> > Thanks. I'll try do this in that way. But I need to disable/enable
> > ACPI PM timer only on suspend/resume, so I'll use suspend/resume
> > callbacks.
>
> Why? What's the point of keeping it running when nothing uses it?
>
> Thanks,
>
>         tglx

In case of Intel CPUs the watchdog (iTCO/wdat_wdt) is driven by ACPI PM
Timer. But it may also be used by others that I don't know about, so I don't
want to disable it.

Best
Marek