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

From: Shuah Khan <skhan@linuxfoundation.org>
To: Huang Rui <ray.huang@amd.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Borislav Petkov <bp@suse.de>, Ingo Molnar <mingo@kernel.org>,
	linux-pm@vger.kernel.org
Cc: Deepak Sharma <deepak.sharma@amd.com>,
	Alex Deucher <alexander.deucher@amd.com>,
	Mario Limonciello <mario.limonciello@amd.com>,
	Nathan Fontenot <nathan.fontenot@amd.com>,
	Jinzhou Su <Jinzhou.Su@amd.com>,
	Xiaojian Du <Xiaojian.Du@amd.com>,
	linux-kernel@vger.kernel.org, x86@kernel.org,
	Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [PATCH 13/19] cpupower: add the function to check amd-pstate enabled
Date: Thu, 9 Sep 2021 16:16:21 -0600	[thread overview]
Message-ID: <50412248-179d-3548-aeb0-d912a14a152f@linuxfoundation.org> (raw)
In-Reply-To: <20210908150001.3702552-14-ray.huang@amd.com>

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?

> 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
> 