Support the new resolve_freq cpufreq callback which resolves a target
frequency to a driver-supported frequency without actually setting it.
The target frequency and resolved frequency table entry are cached so
that a subsequent fast_switch operation may avoid the frequency table
walk assuming the requested target frequency is the same.
Suggested-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
Signed-off-by: Steve Muckle <smuc...@linaro.org>
---
drivers/cpufreq/acpi-cpufreq.c | 56 ++++++++++++++++++++++++++++++++----------
1 file changed, 43 insertions(+), 13 deletions(-)
diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 7f38fb55f223..d87962eda1ed 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -66,6 +66,8 @@ enum {
struct acpi_cpufreq_data {
struct cpufreq_frequency_table *freq_table;
+ unsigned int cached_lookup_freq;
+ struct cpufreq_frequency_table *cached_lookup_entry;
unsigned int resume;
unsigned int cpu_feature;
unsigned int acpi_perf_cpu;
@@ -458,26 +460,53 @@ static int acpi_cpufreq_target(struct cpufreq_policy
*policy,
return result;
}
-unsigned int acpi_cpufreq_fast_switch(struct cpufreq_policy *policy,
- unsigned int target_freq)
+/*
+ * Find the closest frequency above target_freq.
+ *
+ * The table is sorted in the reverse order with respect to the
+ * frequency and all of the entries are valid (see the initialization).
+ */
+static inline struct cpufreq_frequency_table
+*lookup_freq(struct cpufreq_frequency_table *table, unsigned int target_freq)
{
- struct acpi_cpufreq_data *data = policy->driver_data;
- struct acpi_processor_performance *perf;
- struct cpufreq_frequency_table *entry;
- unsigned int next_perf_state, next_freq, freq;
+ struct cpufreq_frequency_table *entry = table;
+ unsigned int freq;
- /*
- * Find the closest frequency above target_freq.
- *
- * The table is sorted in the reverse order with respect to the
- * frequency and all of the entries are valid (see the initialization).
- */
- entry = data->freq_table;
do {
entry++;
freq = entry->frequency;
} while (freq >= target_freq && freq != CPUFREQ_TABLE_END);
entry--;
+
+ return entry;
+}
+
+unsigned int acpi_cpufreq_resolve_freq(struct cpufreq_policy *policy,
+ unsigned int target_freq)
+{
+ struct acpi_cpufreq_data *data = policy->driver_data;
+ struct cpufreq_frequency_table *entry;
+
+ data->cached_lookup_freq = target_freq;
+ entry = lookup_freq(data->freq_table, target_freq);
+ data->cached_lookup_entry = entry;
+
+ return entry->frequency;
+}
+
+unsigned int acpi_cpufreq_fast_switch(struct cpufreq_policy *policy,
+ unsigned int target_freq)
+{
+ struct acpi_cpufreq_data *data = policy->driver_data;
+ struct acpi_processor_performance *perf;
+ struct cpufreq_frequency_table *entry;
+ unsigned int next_perf_state, next_freq;
+
+ if (data->cached_lookup_entry &&
+ data->cached_lookup_freq == target_freq)
+ entry = data->cached_lookup_entry;
+ else
+ entry = lookup_freq(data->freq_table, target_freq);
next_freq = entry->frequency;
next_perf_state = entry->driver_data;
@@ -918,6 +947,7 @@ static struct cpufreq_driver acpi_cpufreq_driver = {
.verify = cpufreq_generic_frequency_table_verify,
.target_index = acpi_cpufreq_target,
.fast_switch = acpi_cpufreq_fast_switch,
+ .resolve_freq = acpi_cpufreq_resolve_freq,
.bios_limit = acpi_processor_get_bios_limit,
.init = acpi_cpufreq_cpu_init,
.exit = acpi_cpufreq_cpu_exit,
--
2.4.10
