[PATCH v4 1/5] cpufreq: Don't wait for CPU to going offline to restart governor

[skannan@codeaurora.org (Saravana Kannan)]

There's no need to wait for the CPU going down to fully go offline to
restart the governor. We can stop the governor, change policy->cpus and
immediately restart the governor. This should reduce the time without any
CPUfreq monitoring and also help future patches with simplifying the code.

Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
---
 drivers/cpufreq/cpufreq.c | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 62259d2..ee0eb7b 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1390,6 +1390,21 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
 		cpufreq_driver->stop_cpu(policy);
 	}
 
+	down_write(&policy->rwsem);
+	cpumask_clear_cpu(cpu, policy->cpus);
+	up_write(&policy->rwsem);
+
+	if (cpus > 1 && has_target()) {
+		ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
+		if (!ret)
+			ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
+
+		if (ret) {
+			pr_err("%s: Failed to start governor\n", __func__);
+			return ret;
+		}
+	}
+
 	return 0;
 }
 
@@ -1410,15 +1425,12 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
 		return -EINVAL;
 	}
 
-	down_write(&policy->rwsem);
+	down_read(&policy->rwsem);
 	cpus = cpumask_weight(policy->cpus);
-
-	if (cpus > 1)
-		cpumask_clear_cpu(cpu, policy->cpus);
-	up_write(&policy->rwsem);
+	up_read(&policy->rwsem);
 
 	/* If cpu is last user of policy, free policy */
-	if (cpus == 1) {
+	if (cpus == 0) {
 		if (has_target()) {
 			ret = __cpufreq_governor(policy,
 					CPUFREQ_GOV_POLICY_EXIT);
@@ -1447,15 +1459,6 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
 
 		if (!cpufreq_suspended)
 			cpufreq_policy_free(policy);
-	} else if (has_target()) {
-		ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
-		if (!ret)
-			ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
-
-		if (ret) {
-			pr_err("%s: Failed to start governor\n", __func__);
-			return ret;
-		}
 	}
 
 	per_cpu(cpufreq_cpu_data, cpu) = NULL;
-- 
1.8.2.1

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