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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Thu, 12 May 2022 17:03:48 +0200
Message-ID: <CAJZ5v0gvHO=2ZwdpQrgMufGFtkEcG-K9zEqoFBYys36qAhTE4Q@mail.gmail.com>
Subject: Re: [PATCH v1 1/5] ACPI: CPPC: Check _OSC for flexible address space
To:     Sudeep Holla <sudeep.holla@arm.com>,
        Pierre Gondois <pierre.gondois@arm.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Ionela Voinescu <Ionela.Voinescu@arm.com>,
        Dietmar Eggemann <Dietmar.Eggemann@arm.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Robert Moore <robert.moore@intel.com>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" <devel@acpica.org>
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On Wed, May 11, 2022 at 4:17 PM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Wed, May 11, 2022 at 03:45:55PM +0200, Pierre Gondois wrote:
> > ACPI 6.2 Section 6.2.11.2 'Platform-Wide OSPM Capabilities':
> >   Starting with ACPI Specification 6.2, all _CPC registers can be in
> >   PCC, System Memory, System IO, or Functional Fixed Hardware address
> >   spaces. OSPM support for this more flexible register space scheme is
> >   indicated by the “Flexible Address Space for CPPC Registers” _OSC bit
> >
> > Otherwise (cf ACPI 6.1, s8.4.7.1.1.X), _CPC registers must be in:
> > - PCC or Functional Fixed Hardware address space if defined
> > - SystemMemory address space (NULL register) if not defined
> >
> > Add the corresponding _OSC bit and check it when parsing _CPC objects.
> >
>
> Looks good, other than a minor nit below. Feel free to ignore that or
> check what is Rafael's preference. Otherwise,
>
> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
>
> > Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
> > ---
> >  drivers/acpi/bus.c       | 18 ++++++++++++++++++
> >  drivers/acpi/cppc_acpi.c |  9 +++++++++
> >  include/linux/acpi.h     |  2 ++
> >  3 files changed, 29 insertions(+)
> >
> [...]
>
> > diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> > index d7136d13aa44..977d74d0465b 100644
> > --- a/include/linux/acpi.h
> > +++ b/include/linux/acpi.h
> > @@ -574,6 +574,7 @@ acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context);
> >  #define OSC_SB_OSLPI_SUPPORT                 0x00000100
> >  #define OSC_SB_CPC_DIVERSE_HIGH_SUPPORT              0x00001000
> >  #define OSC_SB_GENERIC_INITIATOR_SUPPORT     0x00002000
> > +#define OSC_SB_CPC_FLEXIBLE_ADR_SP           0x00004000
>
> I would prefer ADR_SPACE instead of ADR_SP.

Yes, please make this change.