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

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Date:   Tue, 20 Jun 2023 12:24:32 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     "Rafael J . Wysocki" <rafael@...nel.org>
CC:     Len Brown <lenb@...nel.org>, Huang Rui <ray.huang@....com>,
        <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>,
        Gautham Ranjal Shenoy <gautham.shenoy@....com>,
        Wyes Karny <Wyes.Karny@....com>,
        Perry Yuan <perry.yuan@....com>,
        "Mario Limonciello" <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_Programming_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