linux-kernel - [PATCH v1] cpufreq: preserve freq_table

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Message-Id: <20251011072420.11495-1-zhangzihuan@kylinos.cn>
Date: Sat, 11 Oct 2025 15:24:20 +0800
From: zzhwaxy <zhangzihuan@...inos.cn>
To: "Rafael J . Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc: zhenglifeng <zhenglifeng1@...wei.com>,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Zihuan Zhang <zhangzihuan@...inos.cn>
Subject: [PATCH v1] cpufreq: preserve freq_table_sorted across suspend/hibernate

From: Zihuan Zhang <zhangzihuan@...inos.cn>

During S3/S4 suspend and resume, cpufreq policies are not freed or
recreated; the freq_table and policy structure remain intact. However,
set_freq_table_sorted() currently resets policy->freq_table_sorted to
UNSORTED unconditionally, which is unnecessary since the table order
does not change across suspend/resume.

This patch adds a check to skip validation if policy->freq_table_sorted
is already ASCENDING or DESCENDING. This avoids unnecessary traversal
of the frequency table on S3/S4 resume or repeated online events,
reducing overhead while preserving correctness.

Signed-off-by: Zihuan Zhang <zhangzihuan@...inos.cn>
---
 drivers/cpufreq/cpufreq.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 852e024facc3..4a27f6cb07d3 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1421,9 +1421,12 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy,
 		 * If there is a problem with its frequency table, take it
 		 * offline and drop it.
 		 */
-		ret = cpufreq_table_validate_and_sort(policy);
-		if (ret)
-			goto out_offline_policy;
+		if (policy->freq_table_sorted != CPUFREQ_TABLE_SORTED_ASCENDING &&
+		    policy->freq_table_sorted != CPUFREQ_TABLE_SORTED_DESCENDING) {
+			ret = cpufreq_table_validate_and_sort(policy);
+			if (ret)
+				goto out_offline_policy;
+		}
 
 		/* related_cpus should at least include policy->cpus. */
 		cpumask_copy(policy->related_cpus, policy->cpus);
-- 
2.25.1