cpufreq: optimize cpufreq_notify_transition()

cpufreq_notify_transition() calls __cpufreq_notify_transition() for each
CPU of a policy. There is a lot of code in __cpufreq_notify_transition()
though which isn't required to be executed for each CPU, like checking
about disabled cpufreq or irqs, adjusting jiffies, updating cpufreq
stats and some debug print messages.

This commit merges __cpufreq_notify_transition() into
cpufreq_notify_transition() and modifies cpufreq_notify_transition() to
execute minimum amount of code for each CPU.

Also fix the kerneldoc for cpufreq_notify_transition() while at it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 075d18f..b79c532 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -300,8 +300,19 @@ static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 #endif
 }
 
-static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
-               struct cpufreq_freqs *freqs, unsigned int state)
+/**
+ * cpufreq_notify_transition - Notify frequency transition and adjust_jiffies.
+ * @policy: cpufreq policy to enable fast frequency switching for.
+ * @freqs: contain details of the frequency update.
+ * @state: set to CPUFREQ_PRECHANGE or CPUFREQ_POSTCHANGE.
+ *
+ * This function calls the transition notifiers and the "adjust_jiffies"
+ * function. It is called twice on all CPU frequency changes that have
+ * external effects.
+ */
+static void cpufreq_notify_transition(struct cpufreq_policy *policy,
+                                     struct cpufreq_freqs *freqs,
+                                     unsigned int state)
 {
        BUG_ON(irqs_disabled());
 
@@ -313,54 +324,44 @@ static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
                 state, freqs->new);
 
        switch (state) {
-
        case CPUFREQ_PRECHANGE:
-               /* 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
                 * "old frequency".
                 */
                if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
-                       if ((policy) && (policy->cpu == freqs->cpu) &&
-                           (policy->cur) && (policy->cur != freqs->old)) {
+                       if (policy->cur && (policy->cur != freqs->old)) {
                                pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
                                         freqs->old, policy->cur);
                                freqs->old = policy->cur;
                        }
                }
-               srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
-                               CPUFREQ_PRECHANGE, freqs);
+
+               for_each_cpu(freqs->cpu, policy->cpus) {
+                       srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
+                                                CPUFREQ_PRECHANGE, freqs);
+               }
+
                adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
                break;
 
        case CPUFREQ_POSTCHANGE:
                adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
-               pr_debug("FREQ: %lu - CPU: %lu\n",
-                        (unsigned long)freqs->new, (unsigned long)freqs->cpu);
-               trace_cpu_frequency(freqs->new, freqs->cpu);
+               pr_debug("FREQ: %u - CPUs: %*pbl\n", freqs->new,
+                        cpumask_pr_args(policy->cpus));
+
+               for_each_cpu(freqs->cpu, policy->cpus) {
+                       trace_cpu_frequency(freqs->new, freqs->cpu);
+                       srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
+                                                CPUFREQ_POSTCHANGE, freqs);
+               }
+
                cpufreq_stats_record_transition(policy, freqs->new);
-               srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
-                               CPUFREQ_POSTCHANGE, freqs);
-               if (likely(policy) && likely(policy->cpu == freqs->cpu))
-                       policy->cur = freqs->new;
-               break;
+               policy->cur = freqs->new;
        }
 }
 
-/**
- * cpufreq_notify_transition - call notifier chain and adjust_jiffies
- * on frequency transition.
- *
- * This function calls the transition notifiers and the "adjust_jiffies"
- * function. It is called twice on all CPU frequency changes that have
- * external effects.
- */
-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);
-}
-
 /* Do post notifications when there are chances that transition has failed */
 static void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
                struct cpufreq_freqs *freqs, int transition_failed)