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cpufreq: Add stop CPU callback to cpufreq_driver interface 

This callback allows the driver to do clean up before the CPU is
completely down and its state cannot be modified.  This is used
by the intel_pstate driver to reduce the requested P state prior to
the core going away.  This is required because the requested P state
of the offline core is used to select the package P state. This
effectively sets the floor package P state to the requested P state on
the offline core.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
[rjw: Minor modifications]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
hifive-unleashed-5.1
Dirk Brandewie 2014-03-19 08:45:53 -07:00 committed by Rafael J. Wysocki
parent bda9f552f9
commit 367dc4aa93
3 changed files with 10 additions and 1 deletions
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8
Documentation/cpu-freq/cpu-drivers.txt
View File

@ -61,7 +61,13 @@ target_index - See below on the differences.
And optionally
cpufreq_driver.exit - A pointer to a per-CPU cleanup function.
cpufreq_driver.exit - A pointer to a per-CPU cleanup
function called during CPU_POST_DEAD
phase of cpu hotplug process.
cpufreq_driver.stop_cpu - A pointer to a per-CPU stop function
called during CPU_DOWN_PREPARE phase of
cpu hotplug process.
cpufreq_driver.resume - A pointer to a per-CPU resume function
which is called with interrupts disabled

2
drivers/cpufreq/cpufreq.c
View File

@ -1337,6 +1337,8 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
pr_debug("%s: policy Kobject moved to cpu: %d from: %d\n",
__func__, new_cpu, cpu);
}
} else if (cpufreq_driver->stop_cpu && cpufreq_driver->setpolicy) {
cpufreq_driver->stop_cpu(policy);
}
return 0;

1
include/linux/cpufreq.h
View File

@ -227,6 +227,7 @@ struct cpufreq_driver {
int (*bios_limit) (int cpu, unsigned int *limit);
int (*exit) (struct cpufreq_policy *policy);
void (*stop_cpu) (struct cpufreq_policy *policy);
int (*suspend) (struct cpufreq_policy *policy);
int (*resume) (struct cpufreq_policy *policy);
struct freq_attr **attr;