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Commit 99d14d0e authored by Viresh Kumar's avatar Viresh Kumar Committed by Rafael J. Wysocki
Browse files

cpufreq: Process remote callbacks from any CPU if the platform permits 



On many platforms, CPUs can do DVFS across cpufreq policies. i.e CPU
from policy-A can change frequency of CPUs belonging to policy-B.

This is quite common in case of ARM platforms where we don't
configure any per-cpu register.

Add a flag to identify such platforms and update
cpufreq_can_do_remote_dvfs() to allow remote callbacks if this flag is
set.

Also enable the flag for cpufreq-dt driver which is used only on ARM
platforms currently.

Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Acked-by: default avatarSaravana Kannan <skannan@codeaurora.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 674e7541

drivers/cpufreq/cpufreq-dt.c

+1 −0
Original line number Diff line number Diff line
@@ -274,6 +274,7 @@ static int cpufreq_init(struct cpufreq_policy *policy) 
		transition_latency = CPUFREQ_ETERNAL;



	policy->cpuinfo.transition_latency = transition_latency;

	policy->dvfs_possible_from_any_cpu = true;



	return 0;

include/linux/cpufreq.h

+16 −2
Original line number Diff line number Diff line
@@ -127,6 +127,15 @@ struct cpufreq_policy { 
	 */

	unsigned int		transition_delay_us;



	/*

	 * Remote DVFS flag (Not added to the driver structure as we don't want

	 * to access another structure from scheduler hotpath).

	 *

	 * Should be set if CPUs can do DVFS on behalf of other CPUs from

	 * different cpufreq policies.

	 */

	bool			dvfs_possible_from_any_cpu;



	 /* Cached frequency lookup from cpufreq_driver_resolve_freq. */

	unsigned int cached_target_freq;

	int cached_resolved_idx;
@@ -564,8 +573,13 @@ struct governor_attr { 


static inline bool cpufreq_can_do_remote_dvfs(struct cpufreq_policy *policy)

{

	/* Allow remote callbacks only on the CPUs sharing cpufreq policy */

	if (cpumask_test_cpu(smp_processor_id(), policy->cpus))

	/*

	 * Allow remote callbacks if:

	 * - dvfs_possible_from_any_cpu flag is set

	 * - the local and remote CPUs share cpufreq policy

	 */

	if (policy->dvfs_possible_from_any_cpu ||

	    cpumask_test_cpu(smp_processor_id(), policy->cpus))

		return true;



	return false;