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SubjectRe: [PATCH, RFC 02/22] cpufreq: ARM_DT_BL_CPUFREQ needs ARM_CPU_TOPOLOGY
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On Friday, May 03, 2013 10:21:45 AM Viresh Kumar wrote:
> On 2 May 2013 20:46, Arnd Bergmann <arnd@arndb.de> wrote:
> > The big.LITTLE cpufreq driver uses the CPU topology API, which
> > needs to be reflected in Kconfig to prevent broken configurations.
> >
> > warning: (ARM_DT_BL_CPUFREQ) selects ARM_BIG_LITTLE_CPUFREQ which
> > has unmet direct dependencies (ARCH_HAS_CPUFREQ && CPU_FREQ && ARM && ARM_CPU_TOPOLOGY)
> >
> > Cc: Rafael J. Wysocki <rjw@sisk.pl>
> > Cc: Viresh Kumar <viresh.kumar@linaro.org>
> > Cc: cpufreq@vger.kernel.org
> > Cc: linux-pm@vger.kernel.org
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > drivers/cpufreq/Kconfig.arm | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> > index f3af18b..3fd6bdf 100644
> > --- a/drivers/cpufreq/Kconfig.arm
> > +++ b/drivers/cpufreq/Kconfig.arm
> > @@ -10,6 +10,7 @@ config ARM_DT_BL_CPUFREQ
> > tristate "Generic ARM big LITTLE CPUfreq driver probed via DT"
> > select ARM_BIG_LITTLE_CPUFREQ
> > depends on OF && HAVE_CLK
> > + depends on ARM_CPU_TOPOLOGY
> > help
> > This enables the Generic CPUfreq driver for ARM big.LITTLE platform.
> > This gets frequency tables from DT.
>
> This Kconfig thing has always been confusing to me. This is how the code looks
> currently.
>
> config ARM_BIG_LITTLE_CPUFREQ
> tristate
> depends on ARM_CPU_TOPOLOGY
>
> config ARM_DT_BL_CPUFREQ
> tristate "Generic ARM big LITTLE CPUfreq driver probed via DT"
> select ARM_BIG_LITTLE_CPUFREQ
> depends on OF && HAVE_CLK
> help
> This enables the Generic CPUfreq driver for ARM big.LITTLE platform.
> This gets frequency tables from DT.
>
> Because all ARM big LITTLE cpufreq stuff have dependency on
> ARM_CPU_TOPOLOGY, i have added dependency at a common place. So that
> we don't end up adding this in every glue layer driver. How should this be done?

First, there's no rule of thumb here as far as I can say.

In this particular case I think it is OK to make both ARM_DT_BL_CPUFREQ and
ARM_BIG_LITTLE_CPUFREQ depend on ARM_CPU_TOPOLOGY, because (in theory?) the
latter may be set without the former (unless you want to make ARM_DT_BL_CPUFREQ
depend on ARM_BIG_LITTLE_CPUFREQ, but then it may be kind of confusing to
users).

Thanks,
Rafael


--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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