linux-kernel - Re: [PATCH v2] cpufreq: Fix per-policy boost behavior after CPU hotplug

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Date: Thu, 13 Jun 2024 14:50:54 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: PoShao Chen <poshao.chen@...iatek.com>
Cc: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	rafael@...nel.org, clive.lin@...iatek.com, ccj.yeh@...iatek.com,
	ching-hao.hsu@...iatek.com
Subject: Re: [PATCH v2] cpufreq: Fix per-policy boost behavior after CPU
 hotplug

On 12-06-24, 11:31, PoShao Chen wrote:
> This patch fixes the behavior of the cpufreq boost when the
> global boost flag is toggled during CPU hotplug offline. This action
> previously led to incorrect scaling_max_freq values when the CPU was
> brought back online. The issue also manifested as incorrect
> scaling_cur_freq under the performance governor.
> 
> For example, after the following operations, even if the global boost
> is disabled, the resulting scaling_max_freq and scaling_cur_freq
> will still reflect the settings of an enabled boost.
> 
> $ echo performance > /sys/devices/system/cpu/cpufreq/policy7/scaling_governor
> $ cat /sys/devices/system/cpu/cpufreq/policy7/scaling_cur_freq
> 3200000
> $ cat /sys/devices/system/cpu/cpufreq/policy7/scaling_max_freq
> 3200000
> 
> $ echo 1 > /sys/devices/system/cpu/cpufreq/boost
> $ cat /sys/devices/system/cpu/cpufreq/policy7/scaling_cur_freq
> 3250000
> $ cat /sys/devices/system/cpu/cpufreq/policy7/scaling_max_freq
> 3250000
> 
> $ echo 0 > /sys/devices/system/cpu/cpu7/online
> $ echo 0 > /sys/devices/system/cpu/cpufreq/boost
> $ echo 1 > /sys/devices/system/cpu/cpu7/online
> $ cat /sys/devices/system/cpu/cpufreq/policy7/scaling_cur_freq
> 3250000
> $ cat /sys/devices/system/cpu/cpufreq/policy7/scaling_max_freq
> 3250000

Please try this instead:

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 7c6879efe9ef..bd9fe2b0f032 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -43,6 +43,9 @@ static LIST_HEAD(cpufreq_policy_list);
 #define for_each_inactive_policy(__policy)             \
        for_each_suitable_policy(__policy, false)

+#define for_each_policy(__policy)                       \
+       list_for_each_entry(__policy, &cpufreq_policy_list, policy_list)
+
 /* Iterate over governors */
 static LIST_HEAD(cpufreq_governor_list);
 #define for_each_governor(__governor)                          \
@@ -2815,7 +2818,7 @@ int cpufreq_boost_trigger_state(int state)
        write_unlock_irqrestore(&cpufreq_driver_lock, flags);

        cpus_read_lock();
-       for_each_active_policy(policy) {
+       for_each_policy(policy) {
                policy->boost_enabled = state;
                ret = cpufreq_driver->set_boost(policy, state);
                if (ret) {

-- 
viresh