cpufreq: governors: Reset tunables only for cpufreq_unregister_governor()

Currently, whenever governor->governor() is called for CPUFRREQ_GOV_START event
we reset few tunables of governor. Which isn't correct, as this routine is
called for every cpu hot-[un]plugging event. We should actually be resetting
these only when the governor module is removed and re-installed.

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

3 files changed, 21 insertions, 8 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1cea7a1eac13..0b4be4481433 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1562,6 +1562,9 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
                                                 policy->cpu, event);
         ret = policy->governor->governor(policy, event);
 
+        if (!policy->governor->initialized && (event == CPUFREQ_GOV_START))
+                policy->governor->initialized = 1;
+
         /* we keep one module reference alive for
                         each CPU governed by this CPU */
         if ((event != CPUFREQ_GOV_START) || ret)
@@ -1585,6 +1588,7 @@ int cpufreq_register_governor(struct cpufreq_governor *governor)
 
         mutex_lock(&cpufreq_governor_mutex);
 
+        governor->initialized = 0;
         err = -EBUSY;
         if (__find_governor(governor->name) == NULL) {
                 err = 0;
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 7aaa9b151940..79795c4bf611 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -254,11 +254,6 @@ int cpufreq_governor_dbs(struct dbs_data *dbs_data,
                         return rc;
                 }
 
-                /* policy latency is in nS. Convert it to uS first */
-                latency = policy->cpuinfo.transition_latency / 1000;
-                if (latency == 0)
-                        latency = 1;
-
                 /*
                  * conservative does not implement micro like ondemand
                  * governor, thus we are bound to jiffes/HZ
@@ -270,20 +265,33 @@ int cpufreq_governor_dbs(struct dbs_data *dbs_data,
                         cpufreq_register_notifier(cs_ops->notifier_block,
                                         CPUFREQ_TRANSITION_NOTIFIER);
 
-                        dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
-                                jiffies_to_usecs(10);
+                        if (!policy->governor->initialized)
+                                dbs_data->min_sampling_rate =
+                                        MIN_SAMPLING_RATE_RATIO *
+                                        jiffies_to_usecs(10);
                 } else {
                         od_dbs_info->rate_mult = 1;
                         od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
                         od_ops->powersave_bias_init_cpu(cpu);
-                        od_tuners->io_is_busy = od_ops->io_busy();
+
+                        if (!policy->governor->initialized)
+                                od_tuners->io_is_busy = od_ops->io_busy();
                 }
 
+                if (policy->governor->initialized)
+                        goto unlock;
+
+                /* policy latency is in nS. Convert it to uS first */
+                latency = policy->cpuinfo.transition_latency / 1000;
+                if (latency == 0)
+                        latency = 1;
+
                 /* Bring kernel and HW constraints together */
                 dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
                                 MIN_LATENCY_MULTIPLIER * latency);
                 *sampling_rate = max(dbs_data->min_sampling_rate, latency *
                                 LATENCY_MULTIPLIER);
+unlock:
                 mutex_unlock(&dbs_data->mutex);
 
                 /* Initiate timer time stamp */
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index feb360c8aa88..6bf3f2d12c90 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -183,6 +183,7 @@ static inline unsigned long cpufreq_scale(unsigned long old, u_int div, u_int mu
 
 struct cpufreq_governor {
         char    name[CPUFREQ_NAME_LEN];
+        int     initialized;
         int     (*governor)     (struct cpufreq_policy *policy,
                                  unsigned int event);
         ssize_t (*show_setspeed)        (struct cpufreq_policy *policy,