linux-kernel - Re: [PATCH 2/2] ACPI: let BIOS fall back to legacy handling if PRM disabled

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Message-ID: <CAJZ5v0h=jA8awhGZDYXXX7ybcT-d8BpSoPDZfvJ3+_7tOoK=bw@mail.gmail.com>
Date:   Fri, 2 Jul 2021 16:02:22 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Aubrey Li <aubrey.li@...el.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>
Subject: Re: [PATCH 2/2] ACPI: let BIOS fall back to legacy handling if PRM disabled

On Fri, Jul 2, 2021 at 1:37 PM Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> On Fri, Jul 2, 2021 at 9:03 AM Aubrey Li <aubrey.li@...el.com> wrote:
> >
> > Based on _OSC PRM bit, BIOS can choose switch from legacy handling
> > to using PRM. So if CONFIG_ACPI_PRMT is disabled, this bit should
> > not be set to let BIOS fall back to the legacy handling (such as SMI).
> >
> > Cc: Dan Williams <dan.j.williams@...el.com>
> > Signed-off-by: Aubrey Li <aubrey.li@...ux.intel.com>
> > ---
> >  drivers/acpi/bus.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> > index 60fb6a84..30a3d4a 100644
> > --- a/drivers/acpi/bus.c
> > +++ b/drivers/acpi/bus.c
> > @@ -303,7 +303,9 @@ static void acpi_bus_osc_negotiate_platform_control(void)
> >
> >         capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_HOTPLUG_OST_SUPPORT;
> >         capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_PCLPI_SUPPORT;
> > +#ifdef CONFIG_ACPI_PRMT
> >         capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_PRM_SUPPORT;
> > +#endif
>
> What about using if (IS_ENABLED()) instead of #ifdef?

I've made this change myself and applied the patch with a rewritten
changelog and under a different subject ("ACPI: Do not singal PRM
support if not enabled").

Thanks!