linux-kernel - [PATCH v2] cpufreq/cppc: Take policy->cur into judge when set target

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Message-ID:
 <TYCP286MB24861BA890594C119892FB3DB1F22@TYCP286MB2486.JPNP286.PROD.OUTLOOK.COM>
Date: Wed, 29 May 2024 11:22:26 +0800
From: Riwen Lu <luriwen@...mail.com>
To: rafael@...nel.org,
	viresh.kumar@...aro.org
Cc: linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Riwen Lu <luriwen@...inos.cn>
Subject: [PATCH v2] cpufreq/cppc: Take policy->cur into judge when set target

From: Riwen Lu <luriwen@...inos.cn>

There is a case that desired_perf is exactly the same with the old perf,
but the actual current freq is not. Add a judgment condition to return
only when the three values are exactly the same.

This happened in S3 while the cpufreq governor is set to powersave.
During resume process, the CPU frequency is adjusted to the highest
perf. For the booting CPU, there's a warning that "CPU frequency out of
sync:", because the policy->cur is the lowest_perf while the actual
current frequency is the highest_perf that obtained via
cppc_cpufreq_get_rate(), then set policy->cur to highest_perf. The
governor->limits() intent to configure the CPU frequency to lowest_perf
and the governor->target() returned because the desired_perf is equal to
cpu->perf_ctrls.desired_perf leaving the actual current frequency and
policy->cur are remain the highest_perf. Add a judgement that if
policy->cur is the same with desired_perf to decide whther to return.

Signed-off-by: Riwen Lu <luriwen@...inos.cn>

---
v1 -> v2:
 - Update commit message and email.
---
 drivers/cpufreq/cppc_cpufreq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 15f1d41920a3..802f7c7c0ad8 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -296,7 +296,8 @@ static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,

 	desired_perf = cppc_khz_to_perf(&cpu_data->perf_caps, target_freq);
 	/* Return if it is exactly the same perf */
-	if (desired_perf == cpu_data->perf_ctrls.desired_perf)
+	if (desired_perf == cpu_data->perf_ctrls.desired_perf &&
+	    desired_perf == policy->cur)
 		return ret;

 	cpu_data->perf_ctrls.desired_perf = desired_perf;
-- 
2.25.1