linux-kernel - [PATCH] cpufreq: Add CPU frequency policy change notification support

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Message-ID: <20260120092445.5711-1-TonyWWang-oc@zhaoxin.com>
Date: Tue, 20 Jan 2026 17:24:45 +0800
From: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
To: <rafael@...nel.org>, <viresh.kumar@...aro.org>,
	<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <CobeChen@...oxin.com>, <TimGuo@...oxin.com>, <LeoLiu-oc@...oxin.com>,
	<LindaChai@...oxin.com>
Subject: [PATCH] cpufreq: Add CPU frequency policy change notification support

Implemented CPUFREQ_CHANGE_POLICY notification in cpufreq subsystem.
This enhancement allows kernel modules to be notified when a CPU frequency
policy is modified, facilitating more integrated system management.
The notification is dispatched after a successful governor switch during
policy updates.

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
---
 drivers/cpufreq/cpufreq.c | 2 ++
 include/linux/cpufreq.h   | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a7a69f4d7675..b35fed93bca4 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2707,6 +2707,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
 		ret = cpufreq_start_governor(policy);
 		if (!ret) {
 			pr_debug("governor change\n");
+			blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+						     CPUFREQ_CHANGE_POLICY, policy);
 			return 0;
 		}
 		cpufreq_exit_governor(policy);
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index cc894fc38971..b1cc9138e801 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -528,6 +528,7 @@ static inline void cpufreq_resume(void) {}
 /* Policy Notifiers  */
 #define CPUFREQ_CREATE_POLICY		(0)
 #define CPUFREQ_REMOVE_POLICY		(1)
+#define CPUFREQ_CHANGE_POLICY		(2)
 
 #ifdef CONFIG_CPU_FREQ
 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list);
-- 
2.25.1