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

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Message-ID: <34651625-08eb-46df-8075-4c5a08d15c18@arm.com>
Date: Mon, 16 Jun 2025 20:10:37 +0100
From: Robin Murphy <robin.murphy@....com>
To: 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>
Cc: zhenglifeng1@...wei.com
Subject: Re: [PATCH] cpufreq: Fix initialization with disabled boost

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,