linux-kernel - RE: [PATCH v3 2/3] cpufreq: amd-pstate: Set a fallback policy based on preferred

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Date:   Wed, 21 Jun 2023 04:25:04 +0000
From:   "Yuan, Perry" <Perry.Yuan@....com>
To:     "Limonciello, Mario" <Mario.Limonciello@....com>,
        "Rafael J . Wysocki" <rafael@...nel.org>
CC:     Len Brown <lenb@...nel.org>, "Huang, Ray" <Ray.Huang@....com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "Shenoy, Gautham Ranjal" <gautham.shenoy@....com>,
        "Karny, Wyes" <Wyes.Karny@....com>
Subject: RE: [PATCH v3 2/3] cpufreq: amd-pstate: Set a fallback policy based
 on preferred_profile

[AMD Official Use Only - General]

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@....com>
> Sent: Wednesday, June 21, 2023 1:25 AM
> To: Rafael J . Wysocki <rafael@...nel.org>
> Cc: Len Brown <lenb@...nel.org>; Huang, Ray <Ray.Huang@....com>;
> linux-acpi@...r.kernel.org; linux-kernel@...r.kernel.org; linux-
> pm@...r.kernel.org; Shenoy, Gautham Ranjal
> <gautham.shenoy@....com>; Karny, Wyes <Wyes.Karny@....com>;
> Yuan, Perry <Perry.Yuan@....com>; Limonciello, Mario
> <Mario.Limonciello@....com>
> Subject: [PATCH v3 2/3] cpufreq: amd-pstate: Set a fallback policy based on
> preferred_profile
>
> If a user's configuration doesn't explicitly specify the cpufreq scaling governor
> then the code currently explicitly falls back to 'powersave'. This default is fine
> for notebooks and desktops, but servers and undefined machines should
> default to 'performance'.
>
> Look at the 'preferred_profile' field from the FADT to set this policy
> accordingly.
>
> Link:
> https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/05_ACPI_Software_Progr
> amming_Model/ACPI_Software_Programming_Model.html#fixed-acpi-
> description-table-fadt
> Acked-by: Huang Rui <ray.huang@....com>
> Suggested-by: Wyes Karny <Wyes.Karny@....com>
> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@....com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
> v2->v3:
>  * Move new symbols out of patch 1 into this patch
>  * Add Ray's tag
> ---
>  drivers/cpufreq/amd-pstate.c | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index d8269994322e..3546d7db614d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1071,6 +1071,26 @@ static const struct attribute_group
> amd_pstate_global_attr_group = {
>       .attrs = pstate_global_attributes,
>  };
>
> +static bool amd_pstate_acpi_pm_profile_server(void)
> +{
> +     switch (acpi_gbl_FADT.preferred_profile) {
> +     case PM_ENTERPRISE_SERVER:
> +     case PM_SOHO_SERVER:
> +     case PM_PERFORMANCE_SERVER:
> +             return true;
> +     }
> +     return false;
> +}
> +
> +static bool amd_pstate_acpi_pm_profile_undefined(void)
> +{
> +     if (acpi_gbl_FADT.preferred_profile == PM_UNSPECIFIED)
> +             return true;
> +     if (acpi_gbl_FADT.preferred_profile >= NR_PM_PROFILES)
> +             return true;
> +     return false;
> +}
> +
>  static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)  {
>       int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> @@ -1128,10 +1148,14 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
>       policy->max = policy->cpuinfo.max_freq;
>
>       /*
> -      * Set the policy to powersave to provide a valid fallback value in case
> +      * Set the policy to provide a valid fallback value in case
>        * the default cpufreq governor is neither powersave nor
> performance.
>        */
> -     policy->policy = CPUFREQ_POLICY_POWERSAVE;
> +     if (amd_pstate_acpi_pm_profile_server() ||
> +         amd_pstate_acpi_pm_profile_undefined())
> +             policy->policy = CPUFREQ_POLICY_PERFORMANCE;
> +     else
> +             policy->policy = CPUFREQ_POLICY_POWERSAVE;
>
>       if (boot_cpu_has(X86_FEATURE_CPPC)) {
>               ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ,
> &value);
> --
> 2.34.1
Reviewed-by: Perry Yuan <Perry.Yuan@....com>