static int cpufreq_set_policy()

in cpufreq.c [2506:2597]

• 62 lines of code
• 9 McCabe index (conditional complexity)

static int cpufreq_set_policy(struct cpufreq_policy *policy,
			      struct cpufreq_governor *new_gov,
			      unsigned int new_pol)
{
	struct cpufreq_policy_data new_data;
	struct cpufreq_governor *old_gov;
	int ret;

	memcpy(&new_data.cpuinfo, &policy->cpuinfo, sizeof(policy->cpuinfo));
	new_data.freq_table = policy->freq_table;
	new_data.cpu = policy->cpu;
	/*
	 * PM QoS framework collects all the requests from users and provide us
	 * the final aggregated value here.
	 */
	new_data.min = freq_qos_read_value(&policy->constraints, FREQ_QOS_MIN);
	new_data.max = freq_qos_read_value(&policy->constraints, FREQ_QOS_MAX);

	pr_debug("setting new policy for CPU %u: %u - %u kHz\n",
		 new_data.cpu, new_data.min, new_data.max);

	/*
	 * Verify that the CPU speed can be set within these limits and make sure
	 * that min <= max.
	 */
	ret = cpufreq_driver->verify(&new_data);
	if (ret)
		return ret;

	/*
	 * Resolve policy min/max to available frequencies. It ensures
	 * no frequency resolution will neither overshoot the requested maximum
	 * nor undershoot the requested minimum.
	 */
	policy->min = new_data.min;
	policy->max = new_data.max;
	policy->min = __resolve_freq(policy, policy->min, CPUFREQ_RELATION_L);
	policy->max = __resolve_freq(policy, policy->max, CPUFREQ_RELATION_H);
	trace_cpu_frequency_limits(policy);

	policy->cached_target_freq = UINT_MAX;

	pr_debug("new min and max freqs are %u - %u kHz\n",
		 policy->min, policy->max);

	if (cpufreq_driver->setpolicy) {
		policy->policy = new_pol;
		pr_debug("setting range\n");
		return cpufreq_driver->setpolicy(policy);
	}

	if (new_gov == policy->governor) {
		pr_debug("governor limits update\n");
		cpufreq_governor_limits(policy);
		return 0;
	}

	pr_debug("governor switch\n");

	/* save old, working values */
	old_gov = policy->governor;
	/* end old governor */
	if (old_gov) {
		cpufreq_stop_governor(policy);
		cpufreq_exit_governor(policy);
	}

	/* start new governor */
	policy->governor = new_gov;
	ret = cpufreq_init_governor(policy);
	if (!ret) {
		ret = cpufreq_start_governor(policy);
		if (!ret) {
			pr_debug("governor change\n");
			sched_cpufreq_governor_change(policy, old_gov);
			return 0;
		}
		cpufreq_exit_governor(policy);
	}

	/* new governor failed, so re-start old one */
	pr_debug("starting governor %s failed\n", policy->governor->name);
	if (old_gov) {
		policy->governor = old_gov;
		if (cpufreq_init_governor(policy))
			policy->governor = NULL;
		else
			cpufreq_start_governor(policy);
	}

	return ret;
}