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

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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 <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Viresh Kumar 2017-07-28 12:16:39 +05:30 committed by Rafael J. Wysocki
parent 674e75411f
commit 99d14d0e16
2 changed files with 17 additions and 2 deletions
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1
drivers/cpufreq/cpufreq-dt.c
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@ -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;

18
include/linux/cpufreq.h
View File

@ -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;