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cpufreq: Fix serialization of frequency transitions

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Commit 7c30ed ("cpufreq: make sure frequency transitions are serialized")
interacts poorly with systems that have a single core freqency for all
cores.  On such systems we have a single policy for all cores with
several CPUs.  When we do a frequency transition the governor calls the
pre and post change notifiers which causes cpufreq_notify_transition()
per CPU.  Since the policy is the same for all of them all CPUs after
the first and the warnings added are generated by checking a per-policy
flag the warnings will be triggered for all cores after the first.

Fix this by allowing notifier to be called for n times. Where n is the number of
cpus in policy->cpus.

Reported-and-tested-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Viresh Kumar 2013-07-02 16:36:28 +05:30 committed by Rafael J. Wysocki
parent f991fae5c6
commit 266c13d767
2 changed files with 5 additions and 4 deletions
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7
drivers/cpufreq/cpufreq.c
View file

@ -312,11 +312,12 @@ static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
switch (state) { switch (state) {
case CPUFREQ_PRECHANGE: case CPUFREQ_PRECHANGE:
if (WARN(policy->transition_ongoing, if (WARN(policy->transition_ongoing ==
cpumask_weight(policy->cpus),
"In middle of another frequency transition\n")) "In middle of another frequency transition\n"))
return; return;
policy->transition_ongoing = true; policy->transition_ongoing++;
/* detect if the driver reported a value as "old frequency" /* detect if the driver reported a value as "old frequency"
* which is not equal to what the cpufreq core thinks is * which is not equal to what the cpufreq core thinks is
@ -341,7 +342,7 @@ static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
"No frequency transition in progress\n")) "No frequency transition in progress\n"))
return; return;
policy->transition_ongoing = false; policy->transition_ongoing--;
adjust_jiffies(CPUFREQ_POSTCHANGE, freqs); adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
pr_debug("FREQ: %lu - CPU: %lu", (unsigned long)freqs->new, pr_debug("FREQ: %lu - CPU: %lu", (unsigned long)freqs->new,

2
include/linux/cpufreq.h
View file

@ -119,7 +119,7 @@ struct cpufreq_policy {
struct kobject kobj; struct kobject kobj;
struct completion kobj_unregister; struct completion kobj_unregister;
bool transition_ongoing; /* Tracks transition status */ int transition_ongoing; /* Tracks transition status */
}; };
#define CPUFREQ_ADJUST (0) #define CPUFREQ_ADJUST (0)