linux-kernel - [PATCH] cpufreq: Send CPUFREQ_CREATE_POLICY notification after the perf domain creation.

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Message-Id: <20230115235202.24695-1-bhuwz@163.com>
Date:   Mon, 16 Jan 2023 07:52:02 +0800
From:   Vincent Wang <bhuwz@....com>
To:     rafael@...nel.org, viresh.kumar@...aro.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Vincent Wang <vincentwang3@...ovo.com>
Subject: [PATCH] cpufreq: Send CPUFREQ_CREATE_POLICY notification after the perf domain creation.

From: Vincent Wang <vincentwang3@...ovo.com>

We found the following issue during kernel boot on android phone:

[    1.325272][    T1] cpu cpu0: EM: created perf domain
[    1.329317][    T1] cpu cpu4: EM: created perf domain
[    1.337597][   T76] pd_init: no EM found for CPU7
[    1.350849][    T1] cpu cpu7: EM: created perf domain

pd init for cluster2 is executed in a kworker thread and
is earlier than the perf domain creation for cluster2.

pd_init() is called from the cpufreq notification of
CPUFREQ_CREATE_POLICY in cpufreq_online(), which is earlier
than that cpufreq_driver->register_em() is called.

To avoid this issue, cpufreq notification should be sent after
the perf domain creation.

Signed-off-by: Vincent Wang <vincentwang3@...ovo.com>
---
 drivers/cpufreq/cpufreq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 7e56a42750ea..af8836069398 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1430,9 +1430,6 @@ static int cpufreq_online(unsigned int cpu)
 			policy->max_freq_req = NULL;
 			goto out_destroy_policy;
 		}
-
-		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
-				CPUFREQ_CREATE_POLICY, policy);
 	}
 
 	if (cpufreq_driver->get && has_target()) {
@@ -1506,6 +1503,9 @@ static int cpufreq_online(unsigned int cpu)
 		 */
 		if (cpufreq_driver->register_em)
 			cpufreq_driver->register_em(policy);
+
+		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+				CPUFREQ_CREATE_POLICY, policy);
 	}
 
 	ret = cpufreq_init_policy(policy);
-- 
2.25.1