1 files changed, 150 insertions, 23 deletions

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 52cf1f021825..bf8aa45d4f01 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -55,6 +55,10 @@ struct cpu_dbs_info_s {
         struct cpufreq_policy *cur_policy;
         struct work_struct work;
         unsigned int enable;
+        struct cpufreq_frequency_table *freq_table;
+        unsigned int freq_lo;
+        unsigned int freq_lo_jiffies;
+        unsigned int freq_hi_jiffies;
 };
 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
 
@@ -72,15 +76,15 @@ static DEFINE_MUTEX(dbs_mutex);
 
 static struct workqueue_struct  *kondemand_wq;
 
-struct dbs_tuners {
+static struct dbs_tuners {
         unsigned int sampling_rate;
         unsigned int up_threshold;
         unsigned int ignore_nice;
-};
-
-static struct dbs_tuners dbs_tuners_ins = {
+        unsigned int powersave_bias;
+} dbs_tuners_ins = {
         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
         .ignore_nice = 0,
+        .powersave_bias = 0,
 };
 
 static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
@@ -96,6 +100,70 @@ static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
         return retval;
 }
 
+/*
+ * Find right freq to be set now with powersave_bias on.
+ * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
+ * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
+ */
+static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
+                                          unsigned int freq_next,
+                                          unsigned int relation)
+{
+        unsigned int freq_req, freq_reduc, freq_avg;
+        unsigned int freq_hi, freq_lo;
+        unsigned int index = 0;
+        unsigned int jiffies_total, jiffies_hi, jiffies_lo;
+        struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, policy->cpu);
+
+        if (!dbs_info->freq_table) {
+                dbs_info->freq_lo = 0;
+                dbs_info->freq_lo_jiffies = 0;
+                return freq_next;
+        }
+
+        cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
+                        relation, &index);
+        freq_req = dbs_info->freq_table[index].frequency;
+        freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
+        freq_avg = freq_req - freq_reduc;
+
+        /* Find freq bounds for freq_avg in freq_table */
+        index = 0;
+        cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
+                        CPUFREQ_RELATION_H, &index);
+        freq_lo = dbs_info->freq_table[index].frequency;
+        index = 0;
+        cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
+                        CPUFREQ_RELATION_L, &index);
+        freq_hi = dbs_info->freq_table[index].frequency;
+
+        /* Find out how long we have to be in hi and lo freqs */
+        if (freq_hi == freq_lo) {
+                dbs_info->freq_lo = 0;
+                dbs_info->freq_lo_jiffies = 0;
+                return freq_lo;
+        }
+        jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+        jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
+        jiffies_hi += ((freq_hi - freq_lo) / 2);
+        jiffies_hi /= (freq_hi - freq_lo);
+        jiffies_lo = jiffies_total - jiffies_hi;
+        dbs_info->freq_lo = freq_lo;
+        dbs_info->freq_lo_jiffies = jiffies_lo;
+        dbs_info->freq_hi_jiffies = jiffies_hi;
+        return freq_hi;
+}
+
+static void ondemand_powersave_bias_init(void)
+{
+        int i;
+        for_each_online_cpu(i) {
+                struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i);
+                dbs_info->freq_table = cpufreq_frequency_get_table(i);
+                dbs_info->freq_lo = 0;
+        }
+}
+
 /************************** sysfs interface ************************/
 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
 {
@@ -124,6 +192,7 @@ static ssize_t show_##file_name						\
 show_one(sampling_rate, sampling_rate);
 show_one(up_threshold, up_threshold);
 show_one(ignore_nice_load, ignore_nice);
+show_one(powersave_bias, powersave_bias);
 
 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
                 const char *buf, size_t count)
@@ -198,6 +267,27 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
         return count;
 }
 
+static ssize_t store_powersave_bias(struct cpufreq_policy *unused,
+                const char *buf, size_t count)
+{
+        unsigned int input;
+        int ret;
+        ret = sscanf(buf, "%u", &input);
+
+        if (ret != 1)
+                return -EINVAL;
+
+        if (input > 1000)
+                input = 1000;
+
+        mutex_lock(&dbs_mutex);
+        dbs_tuners_ins.powersave_bias = input;
+        ondemand_powersave_bias_init();
+        mutex_unlock(&dbs_mutex);
+
+        return count;
+}
+
 #define define_one_rw(_name) \
 static struct freq_attr _name = \
 __ATTR(_name, 0644, show_##_name, store_##_name)
@@ -205,6 +295,7 @@ __ATTR(_name, 0644, show_##_name, store_##_name)
 define_one_rw(sampling_rate);
 define_one_rw(up_threshold);
 define_one_rw(ignore_nice_load);
+define_one_rw(powersave_bias);
 
 static struct attribute * dbs_attributes[] = {
         &sampling_rate_max.attr,
@@ -212,6 +303,7 @@ static struct attribute * dbs_attributes[] = {
         &sampling_rate.attr,
         &up_threshold.attr,
         &ignore_nice_load.attr,
+        &powersave_bias.attr,
         NULL
 };
 
@@ -234,6 +326,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
         if (!this_dbs_info->enable)
                 return;
 
+        this_dbs_info->freq_lo = 0;
         policy = this_dbs_info->cur_policy;
         cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
         total_ticks = (unsigned int) cputime64_sub(cur_jiffies,
@@ -274,11 +367,18 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
         /* Check for frequency increase */
         if (load > dbs_tuners_ins.up_threshold) {
                 /* if we are already at full speed then break out early */
-                if (policy->cur == policy->max)
-                        return;
-
-                __cpufreq_driver_target(policy, policy->max,
-                        CPUFREQ_RELATION_H);
+                if (!dbs_tuners_ins.powersave_bias) {
+                        if (policy->cur == policy->max)
+                                return;
+
+                        __cpufreq_driver_target(policy, policy->max,
+                                CPUFREQ_RELATION_H);
+                } else {
+                        int freq = powersave_bias_target(policy, policy->max,
+                                        CPUFREQ_RELATION_H);
+                        __cpufreq_driver_target(policy, freq,
+                                CPUFREQ_RELATION_L);
+                }
                 return;
         }
 
@@ -293,37 +393,64 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
          * policy. To be safe, we focus 10 points under the threshold.
          */
         if (load < (dbs_tuners_ins.up_threshold - 10)) {
-                unsigned int freq_next;
-                freq_next = (policy->cur * load) /
+                unsigned int freq_next = (policy->cur * load) /
                         (dbs_tuners_ins.up_threshold - 10);
-
-                __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
+                if (!dbs_tuners_ins.powersave_bias) {
+                        __cpufreq_driver_target(policy, freq_next,
+                                        CPUFREQ_RELATION_L);
+                } else {
+                        int freq = powersave_bias_target(policy, freq_next,
+                                        CPUFREQ_RELATION_L);
+                        __cpufreq_driver_target(policy, freq,
+                                CPUFREQ_RELATION_L);
+                }
         }
 }
 
+/* Sampling types */
+enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
+
 static void do_dbs_timer(void *data)
 {
         unsigned int cpu = smp_processor_id();
         struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
+        /* We want all CPUs to do sampling nearly on same jiffy */
+        int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+        delay -= jiffies % delay;
 
         if (!dbs_info->enable)
                 return;
-
-        lock_cpu_hotplug();
-        dbs_check_cpu(dbs_info);
-        unlock_cpu_hotplug();
-        queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work,
-                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
+        /* Common NORMAL_SAMPLE setup */
+        INIT_WORK(&dbs_info->work, do_dbs_timer, (void *)DBS_NORMAL_SAMPLE);
+        if (!dbs_tuners_ins.powersave_bias ||
+            (unsigned long) data == DBS_NORMAL_SAMPLE) {
+                lock_cpu_hotplug();
+                dbs_check_cpu(dbs_info);
+                unlock_cpu_hotplug();
+                if (dbs_info->freq_lo) {
+                        /* Setup timer for SUB_SAMPLE */
+                        INIT_WORK(&dbs_info->work, do_dbs_timer,
+                                        (void *)DBS_SUB_SAMPLE);
+                        delay = dbs_info->freq_hi_jiffies;
+                }
+        } else {
+                __cpufreq_driver_target(dbs_info->cur_policy,
+                                        dbs_info->freq_lo,
+                                        CPUFREQ_RELATION_H);
+        }
+        queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
 }
 
 static inline void dbs_timer_init(unsigned int cpu)
 {
         struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
+        /* We want all CPUs to do sampling nearly on same jiffy */
+        int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+        delay -= jiffies % delay;
 
-        INIT_WORK(&dbs_info->work, do_dbs_timer, 0);
-        queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work,
-                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
-        return;
+        ondemand_powersave_bias_init();
+        INIT_WORK(&dbs_info->work, do_dbs_timer, NULL);
+        queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
 }
 
 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)