Re: [PATCH 13/19] cpupower: add the function to check amd-pstate enabled

Huang Rui
2021-09-13T11:29:59Z

On Fri, Sep 10, 2021 at 06:16:21AM +0800, Shuah Khan wrote:
> On 9/8/21 8:59 AM, Huang Rui wrote:
> > Introduce the cpupower_amd_pstate_enabled() to check whether the kernel
> > mode enables amd-pstate.
> >
>
> What does "kernel mode" mean? Are you referring to kernel vs.
> firmware mode?

I am referring kernel. In fact, the proccessor which supports the AMD
P-States also supports the legacy ACPI P-States as well. So this API is to
check whether the kernel driver is using amd-pstate or acpi-cpufreq.

I would have explained this, sorry to make you confused, I will explain the
details in the commit log at V2.

Thanks,
Ray

>
> > Signed-off-by: Huang Rui <ray.huang@amd.com>
> > ---
> > tools/power/cpupower/utils/helpers/helpers.h | 5 +++++
> > tools/power/cpupower/utils/helpers/misc.c | 20 ++++++++++++++++++++
> > 2 files changed, 25 insertions(+)
> >
> > diff --git a/tools/power/cpupower/utils/helpers/helpers.h b/tools/power/cpupower/utils/helpers/helpers.h
> > index b4813efdfb00..eb43c14d1728 100644
> > --- a/tools/power/cpupower/utils/helpers/helpers.h
> > +++ b/tools/power/cpupower/utils/helpers/helpers.h
> > @@ -136,6 +136,11 @@ extern int decode_pstates(unsigned int cpu, int boost_states,
> >
> > extern int cpufreq_has_boost_support(unsigned int cpu, int *support,
> > int *active, int * states);
> > +
> > +/* AMD PSTATE enabling **************************/
> > +
> > +extern unsigned long cpupower_amd_pstate_enabled(unsigned int cpu);
> > +
> > /*
> > * CPUID functions returning a single datum
> > */
> > diff --git a/tools/power/cpupower/utils/helpers/misc.c b/tools/power/cpupower/utils/helpers/misc.c
> > index fc6e34511721..07d80775fb68 100644
> > --- a/tools/power/cpupower/utils/helpers/misc.c
> > +++ b/tools/power/cpupower/utils/helpers/misc.c
> > @@ -83,6 +83,26 @@ int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
> > return 0;
> > }
> >
> > +unsigned long cpupower_amd_pstate_enabled(unsigned int cpu)
> > +{
> > + char linebuf[MAX_LINE_LEN];
> > + char path[SYSFS_PATH_MAX];
> > + unsigned long val;
> > + char *endp;
> > +
> > + snprintf(path, sizeof(path),
> > + PATH_TO_CPU "cpu%u/cpufreq/is_amd_pstate_enabled", cpu);
> > +
> > + if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
> > + return 0;
> > +
> > + val = strtoul(linebuf, &endp, 0);
> > + if (endp == linebuf || errno == ERANGE)
> > + return 0;
> > +
> > + return val;
> > +}
> > +
> > #endif /* #if defined(__i386__) || defined(__x86_64__) */
> >
> > /* get_cpustate
> >
>