Re: [PATCH 1/5] acpi: cppc: Allow build with ACPI_CPU_FREQ_PSS config

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On Fri, 2016-08-12 at 09:58 -0700, Hoan Tran wrote:
> Hi Srinivas,
> 
> On Fri, Aug 12, 2016 at 9:52 AM, Srinivas Pandruvada
> <srinivas.pandruvada@linux.intel.com> wrote:
> > 
> > On Fri, 2016-08-12 at 09:35 -0700, Hoan Tran wrote:
> > > 
> > > Hi Srinivas,
> > > 
> > > On Wed, Aug 10, 2016 at 5:17 PM, Srinivas Pandruvada
> > > <srinivas.pandruvada@linux.intel.com> wrote:
> > > > 
> > > > 
> > > > Some newer x86 platforms have support for both _CPC and _PSS
> > > > object. So
> > > > kernel config can have both ACPI_CPU_FREQ_PSS and
> > > > ACPI_CPPC_LIB. So
> > > > remove
> > > > restriction for ACPI_CPPC_LIB to build only when
> > > > ACPI_CPU_FREQ_PSS
> > > > is not
> > > > defined.
> > > > Also for legacy systems with only _PSS, we shouldn't bail out
> > > > if
> > > > acpi_cppc_processor_probe() fails, if ACPI_CPU_FREQ_PSS is also
> > > > defined.
> > > > 
> > > > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.i
> > > > ntel
> > > > .com>
> > > > ---
> > > >  drivers/acpi/Kconfig            | 1 -
> > > >  drivers/acpi/processor_driver.c | 5 ++++-
> > > >  2 files changed, 4 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> > > > index 445ce28..c6bb6aa 100644
> > > > --- a/drivers/acpi/Kconfig
> > > > +++ b/drivers/acpi/Kconfig
> > > > @@ -227,7 +227,6 @@ config ACPI_MCFG
> > > >  config ACPI_CPPC_LIB
> > > >         bool
> > > >         depends on ACPI_PROCESSOR
> > > > -       depends on !ACPI_CPU_FREQ_PSS
> > > From ACPI 6.1 spec, if _CPC is present, its use supersedes the
> > > use of
> > > PSS. So I think, config ACPI_CPU_FREQ_PSS should depend on
> > > !ACPI_CPPC_LIB.
> > > 
> > Distro want to have a single binary kernel image, so they will turn
> > on
> > all configs. So this is not a compile time decision.
> > On runtime if the ACPI contains both tables than _CPC should be
> > used
> > (but that also if the kernel is capable of handling _CPC, as legacy
> > kernel will not).
> Agreed. If so, this "depends on" is not need, right ? And a runtime
> code will be added to decide which is used instead ?
Yes, _CPC will be used if present. 

Thanks,
Srinivas

> 
> Thanks
> Hoan
> 
> > 
> > 
> > Thanks,
> > Srinivas
> > 
> > > 
> > > Thanks
> > > Hoan
> > > 
> > > > 
> > > > 
> > > >         select MAILBOX
> > > >         select PCC
> > > >         help
> > > > diff --git a/drivers/acpi/processor_driver.c
> > > > b/drivers/acpi/processor_driver.c
> > > > index 0553aee..0e0b629 100644
> > > > --- a/drivers/acpi/processor_driver.c
> > > > +++ b/drivers/acpi/processor_driver.c
> > > > @@ -245,8 +245,11 @@ static int __acpi_processor_start(struct
> > > > acpi_device *device)
> > > >                 return 0;
> > > > 
> > > >         result = acpi_cppc_processor_probe(pr);
> > > > -       if (result)
> > > > +       if (result) {
> > > > +#ifndef CONFIG_ACPI_CPU_FREQ_PSS
> > > >                 return -ENODEV;
> > > > +#endif
> > > > +       }
> > > > 
> > > >         if (!cpuidle_get_driver() || cpuidle_get_driver() ==
> > > > &acpi_idle_driver)
> > > >                 acpi_processor_power_init(pr);
> > > > --
> > > > 2.7.4
> > > > 
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