linux-kernel - Re: [PATCH] cpufreq: Send CPUFREQ_CREATE_POLICY notification after the perf domain creation.

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Message-ID: <20230116040720.zjsyp6bolcbnxyqf@vireshk-i7>
Date:   Mon, 16 Jan 2023 09:37:20 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Lukasz Luba <lukasz.luba@....com>, Vincent Wang <bhuwz@....com>
Cc:     rafael@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Wang <vincentwang3@...ovo.com>
Subject: Re: [PATCH] cpufreq: Send CPUFREQ_CREATE_POLICY notification after
 the perf domain creation.

+Lukasz,

Any inputs ?

On 16-01-23, 07:52, Vincent Wang wrote:
> From: Vincent Wang <vincentwang3@...ovo.com>
> 
> We found the following issue during kernel boot on android phone:
> 
> [    1.325272][    T1] cpu cpu0: EM: created perf domain
> [    1.329317][    T1] cpu cpu4: EM: created perf domain
> [    1.337597][   T76] pd_init: no EM found for CPU7
> [    1.350849][    T1] cpu cpu7: EM: created perf domain
> 
> pd init for cluster2 is executed in a kworker thread and
> is earlier than the perf domain creation for cluster2.
> 
> pd_init() is called from the cpufreq notification of
> CPUFREQ_CREATE_POLICY in cpufreq_online(), which is earlier
> than that cpufreq_driver->register_em() is called.
> 
> To avoid this issue, cpufreq notification should be sent after
> the perf domain creation.
> 
> Signed-off-by: Vincent Wang <vincentwang3@...ovo.com>
> ---
>  drivers/cpufreq/cpufreq.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 7e56a42750ea..af8836069398 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1430,9 +1430,6 @@ static int cpufreq_online(unsigned int cpu)
>  			policy->max_freq_req = NULL;
>  			goto out_destroy_policy;
>  		}
> -
> -		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
> -				CPUFREQ_CREATE_POLICY, policy);
>  	}
>  
>  	if (cpufreq_driver->get && has_target()) {
> @@ -1506,6 +1503,9 @@ static int cpufreq_online(unsigned int cpu)
>  		 */
>  		if (cpufreq_driver->register_em)
>  			cpufreq_driver->register_em(policy);
> +
> +		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
> +				CPUFREQ_CREATE_POLICY, policy);
>  	}
>  
>  	ret = cpufreq_init_policy(policy);
> -- 
> 2.25.1

-- 
viresh