linux-kernel - Re: [PATCH v9 03/13] cpufreq: intel_pstate: use common macro definition for Energy Preference Performance(EPP)

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Date:   Tue, 3 Jan 2023 18:31:26 -0600
From:   "Limonciello, Mario" <mario.limonciello@....com>
To:     Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
        ray.huang@....com, viresh.kumar@...aro.org
Cc:     Deepak.Sharma@....com, Nathan.Fontenot@....com,
        Alexander.Deucher@....com, Shimmer.Huang@....com,
        Xiaojian.Du@....com, Li.Meng@....com, wyes.karny@....com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 03/13] cpufreq: intel_pstate: use common macro
 definition for Energy Preference Performance(EPP)

On 12/25/2022 10:34, Perry Yuan wrote:
> make the energy preference performance strings and profiles using one
> common header for intel_pstate driver, then the amd_pstate epp driver can
> use the common header as well. This will simpify the intel_pstate and
> amd_pstate driver.
> 
> Signed-off-by: Perry Yuan <perry.yuan@....com>
> ---
>   drivers/cpufreq/Kconfig.x86    |  2 +-
>   drivers/cpufreq/intel_pstate.c | 13 +++----------
>   include/linux/cpufreq.h        | 10 ++++++++++
>   3 files changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
> index 00476e94db90..f64aef1e093d 100644
> --- a/drivers/cpufreq/Kconfig.x86
> +++ b/drivers/cpufreq/Kconfig.x86
> @@ -36,7 +36,7 @@ config X86_PCC_CPUFREQ
>   
>   config X86_AMD_PSTATE
>   	bool "AMD Processor P-State driver"
> -	depends on X86 && ACPI
> +	depends on X86 && ACPI && X86_INTEL_PSTATE

This doesn't seem right to me.  What if someone didn't compile in Intel 
x86 support for their kernel?  They wouldn't be able to pick X86_AMD_PSTATE.

>   	select ACPI_PROCESSOR
>   	select ACPI_CPPC_LIB if X86_64
>   	select CPU_FREQ_GOV_SCHEDUTIL if SMP
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index ad9be31753b6..93a60fdac0fc 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -640,15 +640,7 @@ static int intel_pstate_set_epb(int cpu, s16 pref)
>    *	4		power
>    */
>   
> -enum energy_perf_value_index {
> -	EPP_INDEX_DEFAULT = 0,
> -	EPP_INDEX_PERFORMANCE,
> -	EPP_INDEX_BALANCE_PERFORMANCE,
> -	EPP_INDEX_BALANCE_POWERSAVE,
> -	EPP_INDEX_POWERSAVE,
> -};
> -
> -static const char * const energy_perf_strings[] = {
> +const char * const energy_perf_strings[] = {
>   	[EPP_INDEX_DEFAULT] = "default",
>   	[EPP_INDEX_PERFORMANCE] = "performance",
>   	[EPP_INDEX_BALANCE_PERFORMANCE] = "balance_performance",
> @@ -656,7 +648,8 @@ static const char * const energy_perf_strings[] = {
>   	[EPP_INDEX_POWERSAVE] = "power",
>   	NULL
>   };
> -static unsigned int epp_values[] = {
> +
> +unsigned int epp_values[] = {
>   	[EPP_INDEX_DEFAULT] = 0, /* Unused index */
>   	[EPP_INDEX_PERFORMANCE] = HWP_EPP_PERFORMANCE,
>   	[EPP_INDEX_BALANCE_PERFORMANCE] = HWP_EPP_BALANCE_PERFORMANCE,
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index d5595d57f4e5..0693269fb775 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -185,6 +185,16 @@ struct cpufreq_freqs {
>   	u8 flags;		/* flags of cpufreq_driver, see below. */
>   };
>   
> +enum energy_perf_value_index {
> +	EPP_INDEX_DEFAULT = 0,
> +	EPP_INDEX_PERFORMANCE,
> +	EPP_INDEX_BALANCE_PERFORMANCE,
> +	EPP_INDEX_BALANCE_POWERSAVE,
> +	EPP_INDEX_POWERSAVE,
> +};
> +extern const char * const energy_perf_strings[];
> +extern unsigned int epp_values[];
> +
>   /* Only for ACPI */
>   #define CPUFREQ_SHARED_TYPE_NONE (0) /* None */
>   #define CPUFREQ_SHARED_TYPE_HW	 (1) /* HW does needed coordination */

I think the right place for these variables and strings is in the cppc 
library source file that is common across CPPC implementations.