From d927d0f2b25b2e2d1979507cb250f7bfce111b0f Mon Sep 17 00:00:00 2001
From: "Prakash, Prashanth" <pprakash@codeaurora.org>
Date: Thu, 11 May 2017 16:39:44 -0600
Subject: [PATCH 18/20] cpufreq / CPPC: Initialize policy->min to lowest
 nonlinear performance

Git-commit: 73808d0fd26b3d3f0f44cc7c469ad1d3c1b570b8
Patch-mainline: v4.13-rc1
References: bsc#1084342

Description of Lowest Perfomance in ACPI 6.1 specification states:
"Lowest Performance is the absolute lowest performance level of
the platform. Selecting a performance level lower than the lowest
nonlinear performance level may actually cause an efficiency penalty,
but should reduce the instantaneous power consumption of the processor.
In traditional terms, this represents the T-state range of performance
levels."

Set the default value of policy->min to Lowest Nonlinear Performance
to avoid any potential efficiency penalty.

Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Alexey Klimov <alexey.klimov@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/cpufreq/cppc_cpufreq.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index e82bb3c30b92..10be285c9055 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -144,10 +144,23 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 	cppc_dmi_max_khz = cppc_get_dmi_max_khz();
 
-	policy->min = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz / cpu->perf_caps.highest_perf;
+	/*
+	 * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
+	 * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
+	 */
+	policy->min = cpu->perf_caps.lowest_nonlinear_perf * cppc_dmi_max_khz /
+		cpu->perf_caps.highest_perf;
 	policy->max = cppc_dmi_max_khz;
-	policy->cpuinfo.min_freq = policy->min;
-	policy->cpuinfo.max_freq = policy->max;
+
+	/*
+	 * Set cpuinfo.min_freq to Lowest to make the full range of performance
+	 * available if userspace wants to use any perf between lowest & lowest
+	 * nonlinear perf
+	 */
+	policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz /
+		cpu->perf_caps.highest_perf;
+	policy->cpuinfo.max_freq = cppc_dmi_max_khz;
+
 	policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num);
 	policy->shared_type = cpu->shared_type;
 
-- 
2.11.0