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Commit 31d13660 authored by DL's avatar DL
Browse files

CPUFREQ: Save and restore max and min scaling freq 

Modify the cpufreq.c driver to save and restore any user modified
scaling_max_freq and scaling_min_freq when CPU hotplugging. By
default, any cap on maximum scaling frequency is removed when a CPU is
taken offline and then brought back online again and the physical
maximum or minimum frequency is restored instead. This patch changes
that behaviour.

Change-Id: If2faa481006ae0ef9a2a5c7c5699386e6ea6f623
parent f86042c1

drivers/cpufreq/cpufreq.c

+21 −1
Original line number Diff line number Diff line
@@ -46,6 +46,8 @@ static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data); 
#ifdef CONFIG_HOTPLUG_CPU

/* This one keeps track of the previously set governor of a removed CPU */

static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);

static DEFINE_PER_CPU(unsigned int, cpu_min_freq);

static DEFINE_PER_CPU(unsigned int, cpu_max_freq);

#endif

static DEFINE_RWLOCK(cpufreq_driver_lock);
@@ -878,6 +880,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) 
#ifdef CONFIG_HOTPLUG_CPU

	struct cpufreq_governor *gov;

	int sibling;

	int min, max;

#endif



	if (cpu_is_offline(cpu))
@@ -951,6 +954,20 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) 
	 */

	cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);



#ifdef CONFIG_HOTPLUG_CPU

	min = per_cpu(cpu_min_freq, cpu);

	if (min) {

		policy->min = per_cpu(cpu_min_freq, cpu);

		pr_debug("Restoring %d min freq for cpu %d\n", policy->min, cpu);

	}



	max = per_cpu(cpu_max_freq, cpu);

	if (max) {

		policy->max = per_cpu(cpu_max_freq, cpu);

		pr_debug("Restoring %d max freq for cpu %d\n", policy->max, cpu);

	}

#endif



	policy->user_policy.min = policy->min;

	policy->user_policy.max = policy->max;
@@ -1050,9 +1067,12 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif 
		__cpufreq_governor(data, CPUFREQ_GOV_STOP);



#ifdef CONFIG_HOTPLUG_CPU

	if (!cpufreq_driver->setpolicy)

	if (!cpufreq_driver->setpolicy) {

		strncpy(per_cpu(cpufreq_cpu_governor, cpu),

			data->governor->name, CPUFREQ_NAME_LEN);

		per_cpu(cpu_min_freq, cpu) = data->min;

		per_cpu(cpu_max_freq, cpu) = data->max;

	}

#endif



	WARN_ON(lock_policy_rwsem_write(cpu));