From 99d14d0e16fadb4de001bacc0ac0786a9ebecf2a Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Fri, 28 Jul 2017 12:16:39 +0530 Subject: [PATCH] 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: Viresh Kumar Acked-by: Saravana Kannan Acked-by: Peter Zijlstra (Intel) Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq-dt.c | 1 + include/linux/cpufreq.h | 18 ++++++++++++++++-- 2 files changed, 17 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c index fef3c2160691..d83ab94d041a 100644 --- a/drivers/cpufreq/cpufreq-dt.c +++ b/drivers/cpufreq/cpufreq-dt.c @@ -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; diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index c4035964e6b3..1981a4a167ce 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -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;