cpufreq: Introducing CPUFREQ_RELATION_E

This newly introduced flag can be applied by a governor to a CPUFreq
relation, when looking for a frequency within the policy table. The
resolution would then only walk through efficient frequencies.

Even with the flag set, the policy max limit will still be honoured. If no
efficient frequencies can be found within the limits of the policy, an
inefficient one would be returned.
Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/acpi-cpufreq.c

@@ -470,7 +470,8 @@ static unsigned int acpi_cpufreq_fast_switch(struct cpufreq_policy *policy,
 	if (policy->cached_target_freq == target_freq)
 		index = policy->cached_resolved_idx;
 	else
-		index = cpufreq_table_find_index_dl(policy, target_freq);
+		index = cpufreq_table_find_index_dl(policy, target_freq,
+						    false);
 
 	entry = &policy->freq_table[index];
 	next_freq = entry->frequency;

drivers/cpufreq/amd_freq_sensitivity.c

@@ -91,7 +91,8 @@ static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy,
 			unsigned int index;
 
 			index = cpufreq_table_find_index_h(policy,
-							   policy->cur - 1);
+							   policy->cur - 1,
+							   relation & CPUFREQ_RELATION_E);
 			freq_next = policy->freq_table[index].frequency;
 		}
 

drivers/cpufreq/cpufreq.c

@@ -2260,8 +2260,16 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
 	    !(cpufreq_driver->flags & CPUFREQ_NEED_UPDATE_LIMITS))
 		return 0;
 
-	if (cpufreq_driver->target)
+	if (cpufreq_driver->target) {
+		/*
+		 * If the driver hasn't setup a single inefficient frequency,
+		 * it's unlikely it knows how to decode CPUFREQ_RELATION_E.
+		 */
+		if (!policy->efficiencies_available)
+			relation &= ~CPUFREQ_RELATION_E;
+
 		return cpufreq_driver->target(policy, target_freq, relation);
+	}
 
 	if (!cpufreq_driver->target_index)
 		return -EINVAL;

drivers/cpufreq/cpufreq_ondemand.c

@@ -83,9 +83,11 @@ static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
 	freq_avg = freq_req - freq_reduc;
 
 	/* Find freq bounds for freq_avg in freq_table */
-	index = cpufreq_table_find_index_h(policy, freq_avg);
+	index = cpufreq_table_find_index_h(policy, freq_avg,
+					   relation & CPUFREQ_RELATION_E);
 	freq_lo = freq_table[index].frequency;
-	index = cpufreq_table_find_index_l(policy, freq_avg);
+	index = cpufreq_table_find_index_l(policy, freq_avg,
+					   relation & CPUFREQ_RELATION_E);
 	freq_hi = freq_table[index].frequency;
 
 	/* Find out how long we have to be in hi and lo freqs */

drivers/cpufreq/powernv-cpufreq.c

@@ -934,7 +934,7 @@ static void powernv_cpufreq_work_fn(struct work_struct *work)
 		policy = cpufreq_cpu_get(cpu);
 		if (!policy)
 			continue;
-		index = cpufreq_table_find_index_c(policy, policy->cur);
+		index = cpufreq_table_find_index_c(policy, policy->cur, false);
 		powernv_cpufreq_target_index(policy, index);
 		cpumask_andnot(&mask, &mask, policy->cpus);
 		cpufreq_cpu_put(policy);
@@ -1022,7 +1022,7 @@ static unsigned int powernv_fast_switch(struct cpufreq_policy *policy,
 	int index;
 	struct powernv_smp_call_data freq_data;
 
-	index = cpufreq_table_find_index_dl(policy, target_freq);
+	index = cpufreq_table_find_index_dl(policy, target_freq, false);
 	freq_data.pstate_id = powernv_freqs[index].driver_data;
 	freq_data.gpstate_id = powernv_freqs[index].driver_data;
 	set_pstate(&freq_data);

drivers/cpufreq/s5pv210-cpufreq.c

@@ -243,7 +243,7 @@ static int s5pv210_target(struct cpufreq_policy *policy, unsigned int index)
 	new_freq = s5pv210_freq_table[index].frequency;
 
 	/* Finding current running level index */
-	priv_index = cpufreq_table_find_index_h(policy, old_freq);
+	priv_index = cpufreq_table_find_index_h(policy, old_freq, false);
 
 	arm_volt = dvs_conf[index].arm_volt;
 	int_volt = dvs_conf[index].int_volt;

include/linux/cpufreq.h

@@ -118,6 +118,13 @@ struct cpufreq_policy {
 	 */
 	bool			strict_target;
 
+	/*
+	 * Set if inefficient frequencies were found in the frequency table.
+	 * This indicates if the relation flag CPUFREQ_RELATION_E can be
+	 * honored.
+	 */
+	bool			efficiencies_available;
+
 	/*
 	 * Preferred average time interval between consecutive invocations of
 	 * the driver to set the frequency for this policy.  To be set by the
@@ -273,6 +280,8 @@ static inline void cpufreq_stats_record_transition(struct cpufreq_policy *policy
 #define CPUFREQ_RELATION_L 0  /* lowest frequency at or above target */
 #define CPUFREQ_RELATION_H 1  /* highest frequency below or at target */
 #define CPUFREQ_RELATION_C 2  /* closest frequency to target */
+/* relation flags */
+#define CPUFREQ_RELATION_E BIT(2) /* Get if possible an efficient frequency */
 
 struct freq_attr {
 	struct attribute attr;
@@ -741,6 +750,22 @@ static inline void dev_pm_opp_free_cpufreq_table(struct device *dev,
 			continue;					\
 		else
 
+/**
+ * cpufreq_for_each_efficient_entry_idx - iterate with index over a cpufreq
+ *	frequency_table excluding CPUFREQ_ENTRY_INVALID and
+ *	CPUFREQ_INEFFICIENT_FREQ frequencies.
+ * @pos: the &struct cpufreq_frequency_table to use as a loop cursor.
+ * @table: the &struct cpufreq_frequency_table to iterate over.
+ * @idx: the table entry currently being processed.
+ * @efficiencies: set to true to only iterate over efficient frequencies.
+ */
+
+#define cpufreq_for_each_efficient_entry_idx(pos, table, idx, efficiencies)	\
+	cpufreq_for_each_valid_entry_idx(pos, table, idx)			\
+		if (efficiencies && (pos->flags & CPUFREQ_INEFFICIENT_FREQ))	\
+			continue;						\
+		else
+
 
 int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
 				    struct cpufreq_frequency_table *table);
@@ -765,14 +790,15 @@ bool policy_has_boost_freq(struct cpufreq_policy *policy);
 
 /* Find lowest freq at or above target in a table in ascending order */
 static inline int cpufreq_table_find_index_al(struct cpufreq_policy *policy,
-					      unsigned int target_freq)
+					      unsigned int target_freq,
+					      bool efficiencies)
 {
 	struct cpufreq_frequency_table *table = policy->freq_table;
 	struct cpufreq_frequency_table *pos;
 	unsigned int freq;
 	int idx, best = -1;
 
-	cpufreq_for_each_valid_entry_idx(pos, table, idx) {
+	cpufreq_for_each_efficient_entry_idx(pos, table, idx, efficiencies) {
 		freq = pos->frequency;
 
 		if (freq >= target_freq)
@@ -786,14 +812,15 @@ static inline int cpufreq_table_find_index_al(struct cpufreq_policy *policy,
 
 /* Find lowest freq at or above target in a table in descending order */
 static inline int cpufreq_table_find_index_dl(struct cpufreq_policy *policy,
-					      unsigned int target_freq)
+					      unsigned int target_freq,
+					      bool efficiencies)
 {
 	struct cpufreq_frequency_table *table = policy->freq_table;
 	struct cpufreq_frequency_table *pos;
 	unsigned int freq;
 	int idx, best = -1;
 
-	cpufreq_for_each_valid_entry_idx(pos, table, idx) {
+	cpufreq_for_each_efficient_entry_idx(pos, table, idx, efficiencies) {
 		freq = pos->frequency;
 
 		if (freq == target_freq)
@@ -816,26 +843,30 @@ static inline int cpufreq_table_find_index_dl(struct cpufreq_policy *policy,
 
 /* Works only on sorted freq-tables */
 static inline int cpufreq_table_find_index_l(struct cpufreq_policy *policy,
-					     unsigned int target_freq)
+					     unsigned int target_freq,
+					     bool efficiencies)
 {
 	target_freq = clamp_val(target_freq, policy->min, policy->max);
 
 	if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
-		return cpufreq_table_find_index_al(policy, target_freq);
+		return cpufreq_table_find_index_al(policy, target_freq,
+						   efficiencies);
 	else
-		return cpufreq_table_find_index_dl(policy, target_freq);
+		return cpufreq_table_find_index_dl(policy, target_freq,
+						   efficiencies);
 }
 
 /* Find highest freq at or below target in a table in ascending order */
 static inline int cpufreq_table_find_index_ah(struct cpufreq_policy *policy,
-					      unsigned int target_freq)
+					      unsigned int target_freq,
+					      bool efficiencies)
 {
 	struct cpufreq_frequency_table *table = policy->freq_table;
 	struct cpufreq_frequency_table *pos;
 	unsigned int freq;
 	int idx, best = -1;
 
-	cpufreq_for_each_valid_entry_idx(pos, table, idx) {
+	cpufreq_for_each_efficient_entry_idx(pos, table, idx, efficiencies) {
 		freq = pos->frequency;
 
 		if (freq == target_freq)
@@ -858,14 +889,15 @@ static inline int cpufreq_table_find_index_ah(struct cpufreq_policy *policy,
 
 /* Find highest freq at or below target in a table in descending order */
 static inline int cpufreq_table_find_index_dh(struct cpufreq_policy *policy,
-					      unsigned int target_freq)
+					      unsigned int target_freq,
+					      bool efficiencies)
 {
 	struct cpufreq_frequency_table *table = policy->freq_table;
 	struct cpufreq_frequency_table *pos;
 	unsigned int freq;
 	int idx, best = -1;
 
-	cpufreq_for_each_valid_entry_idx(pos, table, idx) {
+	cpufreq_for_each_efficient_entry_idx(pos, table, idx, efficiencies) {
 		freq = pos->frequency;
 
 		if (freq <= target_freq)
@@ -879,26 +911,30 @@ static inline int cpufreq_table_find_index_dh(struct cpufreq_policy *policy,
 
 /* Works only on sorted freq-tables */
 static inline int cpufreq_table_find_index_h(struct cpufreq_policy *policy,
-					     unsigned int target_freq)
+					     unsigned int target_freq,
+					     bool efficiencies)
 {
 	target_freq = clamp_val(target_freq, policy->min, policy->max);
 
 	if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
-		return cpufreq_table_find_index_ah(policy, target_freq);
+		return cpufreq_table_find_index_ah(policy, target_freq,
+						   efficiencies);
 	else
-		return cpufreq_table_find_index_dh(policy, target_freq);
+		return cpufreq_table_find_index_dh(policy, target_freq,
+						   efficiencies);
 }
 
 /* Find closest freq to target in a table in ascending order */
 static inline int cpufreq_table_find_index_ac(struct cpufreq_policy *policy,
-					      unsigned int target_freq)
+					      unsigned int target_freq,
+					      bool efficiencies)
 {
 	struct cpufreq_frequency_table *table = policy->freq_table;
 	struct cpufreq_frequency_table *pos;
 	unsigned int freq;
 	int idx, best = -1;
 
-	cpufreq_for_each_valid_entry_idx(pos, table, idx) {
+	cpufreq_for_each_efficient_entry_idx(pos, table, idx, efficiencies) {
 		freq = pos->frequency;
 
 		if (freq == target_freq)
@@ -925,14 +961,15 @@ static inline int cpufreq_table_find_index_ac(struct cpufreq_policy *policy,
 
 /* Find closest freq to target in a table in descending order */
 static inline int cpufreq_table_find_index_dc(struct cpufreq_policy *policy,
-					      unsigned int target_freq)
+					      unsigned int target_freq,
+					      bool efficiencies)
 {
 	struct cpufreq_frequency_table *table = policy->freq_table;
 	struct cpufreq_frequency_table *pos;
 	unsigned int freq;
 	int idx, best = -1;
 
-	cpufreq_for_each_valid_entry_idx(pos, table, idx) {
+	cpufreq_for_each_efficient_entry_idx(pos, table, idx, efficiencies) {
 		freq = pos->frequency;
 
 		if (freq == target_freq)
@@ -959,35 +996,58 @@ static inline int cpufreq_table_find_index_dc(struct cpufreq_policy *policy,
 
 /* Works only on sorted freq-tables */
 static inline int cpufreq_table_find_index_c(struct cpufreq_policy *policy,
-					     unsigned int target_freq)
+					     unsigned int target_freq,
+					     bool efficiencies)
 {
 	target_freq = clamp_val(target_freq, policy->min, policy->max);
 
 	if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
-		return cpufreq_table_find_index_ac(policy, target_freq);
+		return cpufreq_table_find_index_ac(policy, target_freq,
+						   efficiencies);
 	else
-		return cpufreq_table_find_index_dc(policy, target_freq);
+		return cpufreq_table_find_index_dc(policy, target_freq,
+						   efficiencies);
 }
 
 static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 						 unsigned int target_freq,
 						 unsigned int relation)
 {
+	bool efficiencies = policy->efficiencies_available &&
+			    (relation & CPUFREQ_RELATION_E);
+	int idx;
+
+	/* cpufreq_table_index_unsorted() has no use for this flag anyway */
+	relation &= ~CPUFREQ_RELATION_E;
+
 	if (unlikely(policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED))
 		return cpufreq_table_index_unsorted(policy, target_freq,
 						    relation);
-
+retry:
 	switch (relation) {
 	case CPUFREQ_RELATION_L:
-		return cpufreq_table_find_index_l(policy, target_freq);
+		idx = cpufreq_table_find_index_l(policy, target_freq,
+						 efficiencies);
+		break;
 	case CPUFREQ_RELATION_H:
-		return cpufreq_table_find_index_h(policy, target_freq);
+		idx = cpufreq_table_find_index_h(policy, target_freq,
+						 efficiencies);
+		break;
 	case CPUFREQ_RELATION_C:
-		return cpufreq_table_find_index_c(policy, target_freq);
+		idx = cpufreq_table_find_index_c(policy, target_freq,
+						 efficiencies);
+		break;
 	default:
 		WARN_ON_ONCE(1);
 		return 0;
 	}
+
+	if (idx < 0 && efficiencies) {
+		efficiencies = false;
+		goto retry;
+	}
+
+	return idx;
 }
 
 static inline int cpufreq_table_count_valid_entries(const struct cpufreq_policy *policy)
@@ -1027,6 +1087,7 @@ cpufreq_table_set_inefficient(struct cpufreq_policy *policy,
 	cpufreq_for_each_valid_entry(pos, policy->freq_table) {
 		if (pos->frequency == frequency) {
 			pos->flags |= CPUFREQ_INEFFICIENT_FREQ;
+			policy->efficiencies_available = true;
 			return 0;
 		}
 	}