linux-kernel - [PATCH 2/6] cpufreq: acpi: Re-sync CPU boost state on system resume

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Message-Id: <d8651db6d8687a0e37d527267ebfec05f209b1b7.1745315548.git.viresh.kumar@linaro.org>
Date: Tue, 22 Apr 2025 15:23:52 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Lifeng Zheng <zhenglifeng1@...wei.com>
Cc: linux-pm@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Nicholas Chin <nic.c3.14@...il.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/6] cpufreq: acpi: Re-sync CPU boost state on system resume

During suspend/resume cycles, platform firmware may alter the CPU boost
state.

If boost is disabled before suspend, it correctly remains off after
resume. However, if firmware re-enables boost during suspend, the system
may resume with boost frequencies enabled—even when the boost flag was
originally disabled. This violates expected behavior.

Ensure the boost state is re-synchronized with the kernel policy during
system resume to maintain consistency.

Fixes: 2b16c631832d ("cpufreq: ACPI: Remove set_boost in acpi_cpufreq_cpu_init()")
Reported-by: Nicholas Chin <nic.c3.14@...il.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220013
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/cpufreq/acpi-cpufreq.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 7002e8de8098..0ffabf740ff5 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -893,8 +893,19 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	if (perf->states[0].core_frequency * 1000 != freq_table[0].frequency)
 		pr_warn(FW_WARN "P-state 0 is not max freq\n");
 
-	if (acpi_cpufreq_driver.set_boost)
-		policy->boost_supported = true;
+	if (acpi_cpufreq_driver.set_boost) {
+		if (policy->boost_supported) {
+			/*
+			 * The firmware may have altered boost state while the
+			 * CPU was offline (for example during a suspend-resume
+			 * cycle).
+			 */
+			if (policy->boost_enabled != boost_state(cpu))
+				set_boost(policy, policy->boost_enabled);
+		} else {
+			policy->boost_supported = true;
+		}
+	}
 
 	return result;
 
-- 
2.31.1.272.g89b43f80a514