Messages in this thread | | | From | "Michael S. Zick" <> | Subject | Re: [PATCH 1/2] CPUFREQ: Enable acpi-cpufreq driver for VIA/Centaur CPUs | Date | Mon, 8 Jun 2009 16:32:18 -0500 |
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On Mon June 8 2009, Linus Torvalds wrote: > > On Mon, 8 Jun 2009, Harald Welte wrote: > > > > The VIA/Centaur C7, C7-M and Nano CPU's all support ACPI based cpu p-states > > using a MSR interface. The Linux driver just never made use of it, since in > > addition to the check for the EST flag it also checked if the vendor is Intel. > > > > Signed-off-by: Harald Welte <HaraldWelte@viatech.com> > > --- > > arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 3 ++- > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > > diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c > > index 208ecf6..ee03585 100644 > > --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c > > +++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c > > @@ -90,7 +90,8 @@ static int check_est_cpu(unsigned int cpuid) > > { > > struct cpuinfo_x86 *cpu = &cpu_data(cpuid); > > > > - if (cpu->x86_vendor != X86_VENDOR_INTEL || > > + if ((cpu->x86_vendor != X86_VENDOR_INTEL && > > + cpu->x86_vendor != X86_VENDOR_CENTAUR) || > > !cpu_has(cpu, X86_FEATURE_EST)) > > Hmm. This all really should be just > > static int check_est_cpu(unsigned int cpuid) > { > struct cpuinfo_x86 *cpu = &cpu_data(cpuid); > return cpu_has(cpu, X86_FEATURE_EST); > } > > I suspect, with no vendor tests. That's the whole _point_ of CPU features, > after all. > > If some vendor claims EST but doesn't actually support the EST interfaces, > we should just have fixups to clear the bit in the per-vendor cpuinfo > code, not in some random driver. >
Sounds like a plan to me - -
Shall we define a kernel 'cpu-feature' for the internal, adaptive thermal/power/freq controller?
There are at least two cpufreq drivers that need to be able to check for the feature _and_ perhaps the clock/timing routines would need to know if it was there/enabled -
Since it is internal, on-chip, it will not be sending any notifications as it adapts the core clock speed. (so much for 'loops/xSec').
Knowing that it is present and enabled would let the timing routines establish non-loop counting measurements.
Mike > The only thing that makes me nervous about this is how close to 2.6.30 we > are. I'd be happier if this was resolved by doing this as a patch > post-2.6.30, and then adding 'stable@kernel.org' as a Cc: tag, and > backporting it to 2.6.30.1 if no problems appear. > > It's not like this is a regression, I think. > > Does that sound like a reasonable plan? > > Linus > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > >
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