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authorHoan Tran <hotran@apm.com>2016-10-13 10:33:35 -0700
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-10-13 23:10:41 +0200
commitc197d758036d8c77923ae3f88571cf198283107e (patch)
tree9dea7912efc8aa2036eec6c157403643a3e07f5a /drivers
parentabb6627910a1e783c8e034b35b7c80e5e7f98f41 (diff)
downloadlinux-c197d758036d8c77923ae3f88571cf198283107e.tar.gz
cpufreq: CPPC: Correct desired_perf calculation
The desired_perf is an abstract performance number. Its value should
be in the range of [lowest perf, highest perf] of CPPC.
The correct calculation is
  desired_perf = freq * cppc_highest_perf / cppc_dmi_max_khz

And cppc_cpufreq_set_target() returns if desired_perf is exactly
the same with the old perf.

Signed-off-by: Hoan Tran <hotran@apm.com>
Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/cpufreq/cppc_cpufreq.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 99db4227ae38..f7e98fc077c1 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -80,11 +80,17 @@ static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
 {
 	struct cpudata *cpu;
 	struct cpufreq_freqs freqs;
+	u32 desired_perf;
 	int ret = 0;
 
 	cpu = all_cpu_data[policy->cpu];
 
-	cpu->perf_ctrls.desired_perf = (u64)target_freq * policy->max / cppc_dmi_max_khz;
+	desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
+	/* Return if it is exactly the same perf */
+	if (desired_perf == cpu->perf_ctrls.desired_perf)
+		return ret;
+
+	cpu->perf_ctrls.desired_perf = desired_perf;
 	freqs.old = policy->cur;
 	freqs.new = target_freq;