linux-kernel - Re: [PATCH] cpufreq: Fix initialization with disabled boost

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Message-ID: <4b551b8c-6572-4fd1-9bd8-6669aaf69271@huawei.com>
Date: Tue, 17 Jun 2025 10:14:46 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: Robin Murphy <robin.murphy@....com>, Christian Loehle
	<christian.loehle@....com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, linux-pm <linux-pm@...r.kernel.org>, Viresh
 Kumar <viresh.kumar@...aro.org>, "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] cpufreq: Fix initialization with disabled boost

On 2025/6/17 3:10, Robin Murphy wrote:
> On 2025-06-16 6:25 pm, Christian Loehle wrote:
>> The boost_enabled early return in policy_set_boost() caused
>> the boost disabled at initialization to not actually set the
>> initial policy->max, therefore effectively enabling boost while
>> it should have been enabled.
>>
>> Fixes: 27241c8b63bd ("cpufreq: Introduce policy_set_boost()")
> 
> I think it's a bit older than that - I noticed this with 6.15 stable, prior to that refactoring, and from a poke through the history the underlying logic appears to date back to dd016f379ebc ("cpufreq: Introduce a more generic way to set default per-policy boost flag"). Hopefully someone can figure out the appropriate stable backport.
> 
> I can at least confirm that equivalently hacking out the "&& policy->boost_enabled != cpufreq_boost_enabled()" condition previously here does have the desired effect for me of initialising scaling_max_freq correctly at boot, but I'm not sure that's entirely correct on its own...
> 
> Thanks,
> Robin.
> 
>> Reported-by: Robin Murphy <robin.murphy@....com>
>> Signed-off-by: Christian Loehle <christian.loehle@....com>
>> ---
>>   drivers/cpufreq/cpufreq.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>> index d7426e1d8bdd..e85139bd0436 100644
>> --- a/drivers/cpufreq/cpufreq.c
>> +++ b/drivers/cpufreq/cpufreq.c
>> @@ -1630,7 +1630,7 @@ static int cpufreq_online(unsigned int cpu)
>>        */
>>       if (cpufreq_driver->set_boost && policy->boost_supported &&
>>           (new_policy || !cpufreq_boost_enabled())) {
>> -        ret = policy_set_boost(policy, cpufreq_boost_enabled());
>> +        ret = cpufreq_driver->set_boost(policy, cpufreq_boost_enabled());
>>           if (ret) {
>>               /* If the set_boost fails, the online operation is not affected */
>>               pr_info("%s: CPU%d: Cannot %s BOOST\n", __func__, policy->cpu,
> 
> 

I don't quite understand what problem you've met. It semms like you guys
propose that set_boost() should be called no matter what
policy->boost_enabled is. Having more details would help to clarify things,
such as which driver you use and what you expect but not be achieved.