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 09:35 -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.intel
> > .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).

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
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-
> > acpi" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pm"
> in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html