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>
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index 8b1a445..48da5fd 100644
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -61,7 +61,13 @@
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
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 3c56c47..3aa7a7a 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1337,6 +1337,8 @@
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;
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 70929bc..2d2e62c 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -227,6 +227,7 @@
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;