Re: [PATCH 1/2] CPUFREQ: Enable acpi-cpufreq driver for VIA/Centaur CPUs

Michael S. Zick
2009-06-08T21:15:34Z

On Mon June 8 2009, Michael S. Zick wrote:
> On Mon June 8 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))
> > return 0;
> >
>
> For my own internal testing, based on subsequent posts, I simplified
> that to:
>
> static int check_est_cpu(unsigned int cpuid)
> {
> struct cpuinfo_x86 *cpu = &cpu_data(cpuid);
>
> if (!cpu_has(cpu, X86_FEATURE_EST))
> return 0;
>
> return 1;
> }
>
> Have not done anything (yet) to deal with the adaptive controller,
> **which is safe to (not) do on my test system because I know it isn't enabled**
>
> Note: This machine is known to run common, proprietary operating systems,
> so I am also assuming its BIOS ACPI is complete enough.
>
> Note 2: Don't try this unless you have a machine to waste. ;)
>

Phooey, close but no cigar - - -

root@cb01:/sys/devices/system/cpu/cpu0/cpufreq# cat scaling_available_frequencies
1200000 1000000 800000 600000 400000
root@cb01:/sys/devices/system/cpu/cpu0/cpufreq# cat stats/time_in_state
1200000 3281
1000000 120
800000 130
600000 234
400000 52980
root@cb01:/sys/devices/system/cpu/cpu0/cpufreq

It loads, it appears to work, but that lowest 400Mhz has ACPI entries
even though this is a 600Mhz..1200Mhz chip.

Should be fixable -
The code looks like it is "asking" the BIOS for the table ranges -
It needs to sanity check against the limits etched in the silicon for
this particular [mask/process run].

I am thinking, maybe put the min/max GSF into cpu_boot_data.
Will probably need it there to fix e_powersaver anyway.

Mike
> Mike
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