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>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1cea7a1..0b4be44 100644 (file)
--- 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 7aaa9b1..79795c4 100644 (file)
--- 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 feb360c..6bf3f2d 100644 (file)
--- 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,