linux-kernel - RE: [PATCH] ACPI: bus: Fix osc_sb_cppc_not

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Date:   Fri, 24 Jun 2022 17:56:33 +0000
From:   "Yuan, Perry" <Perry.Yuan@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     "Huang, Ray" <Ray.Huang@....com>,
        "Limonciello, Mario" <Mario.Limonciello@....com>,
        Len Brown <lenb@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Fontenot, Nathan" <Nathan.Fontenot@....com>,
        "Su, Jinzhou (Joe)" <Jinzhou.Su@....com>,
        "Huang, Shimmer" <Xinmei.Huang@....com>,
        "Du, Xiaojian" <Xiaojian.Du@....com>,
        "Meng, Li (Jassmine)" <Li.Meng@....com>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: RE: [PATCH] ACPI: bus: Fix osc_sb_cppc_not_supported check

[AMD Official Use Only - General]

Hi Rafael:

> -----Original Message-----
> From: Rafael J. Wysocki <rafael@...nel.org>
> Sent: Saturday, June 25, 2022 12:12 AM
> To: Yuan, Perry <Perry.Yuan@....com>
> Cc: Huang, Ray <Ray.Huang@....com>; Limonciello, Mario
> <Mario.Limonciello@....com>; Rafael J. Wysocki <rafael@...nel.org>; Len
> Brown <lenb@...nel.org>; Mika Westerberg
> <mika.westerberg@...ux.intel.com>; ACPI Devel Maling List <linux-
> acpi@...r.kernel.org>; Linux Kernel Mailing List <linux-kernel@...r.kernel.org>;
> Fontenot, Nathan <Nathan.Fontenot@....com>; Su, Jinzhou (Joe)
> <Jinzhou.Su@....com>; Huang, Shimmer <Xinmei.Huang@....com>; Du,
> Xiaojian <Xiaojian.Du@....com>; Meng, Li (Jassmine) <Li.Meng@....com>;
> Linux PM <linux-pm@...r.kernel.org>
> Subject: Re: [PATCH] ACPI: bus: Fix osc_sb_cppc_not_supported check
> 
> [CAUTION: External Email]
> 
> On Fri, Jun 24, 2022 at 2:00 PM Perry Yuan <Perry.Yuan@....com> wrote:
> >
> > The patch fixs the osc_sb_cppc_not_supported variable checking
> > Otherwise the cppc acpi driver will be failed to register causing AMD
> > pstate driver failed to load when calling acpi_cpc_valid()
> >
> > Fixes: c42fa24b447("ACPI: bus: Avoid using CPPC if not supported by
> > firmware")
> > Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> > ---
> >  drivers/acpi/bus.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c index
> > 4d7c51a33b01..9731e4a1e338 100644
> > --- a/drivers/acpi/bus.c
> > +++ b/drivers/acpi/bus.c
> > @@ -359,7 +359,7 @@ static void
> acpi_bus_osc_negotiate_platform_control(void)
> >         }
> >
> >  #ifdef CONFIG_ACPI_CPPC_LIB
> > -       osc_sb_cppc_not_supported = !(capbuf_ret[OSC_SUPPORT_DWORD] &
> > +       osc_sb_cppc_not_supported = !(capbuf_ret[OSC_SUPPORT_DWORD] &&
> >                         (OSC_SB_CPC_SUPPORT | OSC_SB_CPCV2_SUPPORT));
> 
> This certainly is not a correct fix, because it causes osc_sb_cppc_not_supported
> to always be true if capbuf_ret[OSC_SUPPORT_DWORD] is not zero.
> 
> >  #endif

That is true, I will send another fix solution soon.

Perry  

> >
> > --
> > 2.25.1
> >