acpi-cpufreq: Add comment under ACPI_ADR_SPACE_SYSTEM_IO case
policy->cur is now set by cpufreq core when cpufreq_driver->get() is defined and
so drivers aren't required to set it. When space_id is ACPI_ADR_SPACE_SYSTEM_IO
for acpi cpufreq driver it doesn't set ->get to a valid function pointer and so
policy->cur is required to be set by driver.
This is already followed in acpi-cpufreq driver. This patch adds a comment
describing why we need to set policy->cur from driver.
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index a8dac7b..a1717d7 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -837,7 +837,12 @@
switch (perf->control_register.space_id) {
case ACPI_ADR_SPACE_SYSTEM_IO:
- /* Current speed is unknown and not detectable by IO port */
+ /*
+ * The core will not set policy->cur, because
+ * cpufreq_driver->get is NULL, so we need to set it here.
+ * However, we have to guess it, because the current speed is
+ * unknown and not detectable via IO ports.
+ */
policy->cur = acpi_cpufreq_guess_freq(data, policy->cpu);
break;
case ACPI_ADR_SPACE_FIXED_HARDWARE: