linux-kernel - [RFC 3/9] cpufreq: Add dvfs_possible_from_any

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Date:   Thu,  9 Mar 2017 17:15:13 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rafael Wysocki <rjw@...ysocki.net>, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        smuckle.linux@...il.com, juri.lelli@....com,
        Morten.Rasmussen@....com, patrick.bellasi@....com,
        eas-dev@...ts.linaro.org
Subject: [RFC 3/9] cpufreq: Add dvfs_possible_from_any_cpu policy flag

On many platforms any CPU (from any cpufreq policy) can perform DVFS on
behalf of other CPUs. Add a flag to identify such cpufreq policies.

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

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/cpufreq/cpufreq-dt.c | 1 +
 include/linux/cpufreq.h      | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index c943787d761e..e57b45f20544 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 87165f06a307..9490a314c515 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -120,6 +120,15 @@ struct cpufreq_policy {
 	bool			fast_switch_possible;
 	bool			fast_switch_enabled;
 
+	/*
+	 * 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 any CPU (from same or different policy) can do DVFS
+	 * on behalf of any other CPU.
+	 */
+	bool			dvfs_possible_from_any_cpu;
+
 	 /* Cached frequency lookup from cpufreq_driver_resolve_freq. */
 	unsigned int cached_target_freq;
 	int cached_resolved_idx;
-- 
2.7.1.410.g6faf27b