[PATCH 3.16.y-ckt 041/170] cpufreq: intel_pstate: Fix setting max_perf_pct in performance policy

[Luis Henriques]

3.16.7-ckt1 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali.rohar@xxxxxxxxx>

commit 36b4bed5cd8f6e17019fa7d380e0836872c7b367 upstream.

Code which changes policy to powersave changes also max_policy_pct based on
max_freq. Code which change max_perf_pct has upper limit base on value
max_policy_pct. When policy is changing from powersave back to performance
then max_policy_pct is not changed. Which means that changing max_perf_pct is
not possible to high values if max_freq was too low in powersave policy.

Test case:

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
800000
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
3300000
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
performance
$ cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
100

$ echo powersave > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
$ echo 800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
$ echo 20 > /sys/devices/system/cpu/intel_pstate/max_perf_pct

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
powersave
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
800000
$ cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
20

$ echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
$ echo 3300000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
$ echo 100 > /sys/devices/system/cpu/intel_pstate/max_perf_pct

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
performance
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
3300000
$ cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
24

And now intel_pstate driver allows to set maximal value for max_perf_pct based
on max_policy_pct which is 24 for previous powersave max_freq 800000.

This patch will set default value for max_policy_pct when setting policy to
performance so it will allow to set also max value for max_perf_pct.

Signed-off-by: Pali RohÃr <pali.rohar@xxxxxxxxx>
Acked-by: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 drivers/cpufreq/intel_pstate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 86631cb6f7de..738f5c85b5ca 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -742,6 +742,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
 	if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
 		limits.min_perf_pct = 100;
 		limits.min_perf = int_tofp(1);
+		limits.max_policy_pct = 100;
 		limits.max_perf_pct = 100;
 		limits.max_perf = int_tofp(1);
 		limits.no_turbo = limits.turbo_disabled;
-- 
2.1.0

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