1 files changed, 47 insertions, 14 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 3aa7a7a..abda660 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -331,16 +331,15 @@ static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
  * function. It is called twice on all CPU frequency changes that have
  * external effects.
  */
-void cpufreq_notify_transition(struct cpufreq_policy *policy,
+static void cpufreq_notify_transition(struct cpufreq_policy *policy,
 		struct cpufreq_freqs *freqs, unsigned int state)
 {
 	for_each_cpu(freqs->cpu, policy->cpus)
 		__cpufreq_notify_transition(policy, freqs, state);
 }
-EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
 
 /* Do post notifications when there are chances that transition has failed */
-void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
+static void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
 		struct cpufreq_freqs *freqs, int transition_failed)
 {
 	cpufreq_notify_transition(policy, freqs, CPUFREQ_POSTCHANGE);
@@ -351,7 +350,41 @@ void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
 	cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
 	cpufreq_notify_transition(policy, freqs, CPUFREQ_POSTCHANGE);
 }
-EXPORT_SYMBOL_GPL(cpufreq_notify_post_transition);
+
+void cpufreq_freq_transition_begin(struct cpufreq_policy *policy,
+		struct cpufreq_freqs *freqs)
+{
+wait:
+	wait_event(policy->transition_wait, !policy->transition_ongoing);
+
+	spin_lock(&policy->transition_lock);
+
+	if (unlikely(policy->transition_ongoing)) {
+		spin_unlock(&policy->transition_lock);
+		goto wait;
+	}
+
+	policy->transition_ongoing = true;
+
+	spin_unlock(&policy->transition_lock);
+
+	cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
+}
+EXPORT_SYMBOL_GPL(cpufreq_freq_transition_begin);
+
+void cpufreq_freq_transition_end(struct cpufreq_policy *policy,
+		struct cpufreq_freqs *freqs, int transition_failed)
+{
+	if (unlikely(WARN_ON(!policy->transition_ongoing)))
+		return;
+
+	cpufreq_notify_post_transition(policy, freqs, transition_failed);
+
+	policy->transition_ongoing = false;
+
+	wake_up(&policy->transition_wait);
+}
+EXPORT_SYMBOL_GPL(cpufreq_freq_transition_end);
 
 
 /*********************************************************************
@@ -985,6 +1018,8 @@ static struct cpufreq_policy *cpufreq_policy_alloc(void)
 
 	INIT_LIST_HEAD(&policy->policy_list);
 	init_rwsem(&policy->rwsem);
+	spin_lock_init(&policy->transition_lock);
+	init_waitqueue_head(&policy->transition_wait);
 
 	return policy;
 
@@ -1470,8 +1505,8 @@ static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq,
 	policy = per_cpu(cpufreq_cpu_data, cpu);
 	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
-	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
-	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
+	cpufreq_freq_transition_begin(policy, &freqs);
+	cpufreq_freq_transition_end(policy, &freqs, 0);
 }
 
 /**
@@ -1652,14 +1687,13 @@ void cpufreq_resume(void)
 	cpufreq_suspended = false;
 
 	list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
-		if (__cpufreq_governor(policy, CPUFREQ_GOV_START)
+		if (cpufreq_driver->resume && cpufreq_driver->resume(policy))
+			pr_err("%s: Failed to resume driver: %p\n", __func__,
+				policy);
+		else if (__cpufreq_governor(policy, CPUFREQ_GOV_START)
 		    || __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS))
 			pr_err("%s: Failed to start governor for policy: %p\n",
 				__func__, policy);
-		else if (cpufreq_driver->resume
-		    && cpufreq_driver->resume(policy))
-			pr_err("%s: Failed to resume driver: %p\n", __func__,
-				policy);
 
 		/*
 		 * schedule call cpufreq_update_policy() for boot CPU, i.e. last
@@ -1832,8 +1866,7 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
 			pr_debug("%s: cpu: %d, oldfreq: %u, new freq: %u\n",
 				 __func__, policy->cpu, freqs.old, freqs.new);
 
-			cpufreq_notify_transition(policy, &freqs,
-					CPUFREQ_PRECHANGE);
+			cpufreq_freq_transition_begin(policy, &freqs);
 		}
 
 		retval = cpufreq_driver->target_index(policy, index);
@@ -1842,7 +1875,7 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
 			       __func__, retval);
 
 		if (notify)
-			cpufreq_notify_post_transition(policy, &freqs, retval);
+			cpufreq_freq_transition_end(policy, &freqs, retval);
 	}
 
 out: