Re: [PATCH v2 2/2] cpufreq: fix schedutil not returning to non-boost freq when boost is disabled

[Zhongqiu Han]

Hi Ananthu,

On 9/8/2026 4:30 PM, Ananthu C V wrote:
> Commit 538b0188da46 ("cpufreq: ACPI: Set cpuinfo.max_freq directly if
> max boost is known") introduced a guard for cpuinfo max updates to only
> increase, to preserve driver-set values above the freq table maximum,
> causing cpuinfo max to be stuck at boost frequency even when boost is
> disabled.
>
> Unconditionally track the highest non-boost frequency (max_base_freq)
> in the freq table. When a freq table is available, use max_table_freq/
> max_base_freq instead of cpuinfo->max_freq to control boost values, so
> the value can decrease again when boost is disabled.

This issue does not appear to be limited to schedutil, so the subject
seems too restrictive.

> Fixes: 538b0188da46 ("cpufreq: ACPI: Set cpuinfo.max_freq directly if max boost is known")

I already commented on the Fixes: tag in v1.
https://lore.kernel.org/all/3a20b69e-b072-4723-925f-514d8162e259@xxxxxxxxxxxxxxxx/#t

IMO it should be: 6e39ba4e5a82 ("cpufreq: Add boost_freq_req QoS
request")

Could you please comment on this?

> Signed-off-by: Ananthu C V <ananthu.cv@xxxxxxxxxxxxxxxx>
> ---
>   drivers/cpufreq/cpufreq.c    | 14 +++++++++++++-
>   drivers/cpufreq/freq_table.c |  5 +++++
>   include/linux/cpufreq.h      |  1 +
>   3 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 0d0df986fa3d..a13e72711597 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -574,6 +574,7 @@ static ssize_t show_local_boost(struct cpufreq_policy *policy, char *buf)
>   
>   static int policy_set_boost(struct cpufreq_policy *policy, bool enable)
>   {
> +	unsigned int max_freq;
>   	int ret;
>   
>   	if (policy->boost_enabled == enable)
> @@ -587,7 +588,18 @@ static int policy_set_boost(struct cpufreq_policy *policy, bool enable)
>   		return ret;
>   	}
>   
> -	ret = freq_qos_update_request(&policy->boost_freq_req, policy->cpuinfo.max_freq);
> +	if (policy->freq_table) {

acpi-cpufreq has a freq table but never sets CPUFREQ_BOOST_FREQ, so
max_table_freq == max_base_freq == _PSS P0 here, and the real boost
ceiling kept in cpuinfo.max_freq is lost. It seems that the condition
needs to be "does the freq table list boost frequencies" rather than "is
there a freq table" — e.g. recorded during the table scan, the same way
boost_supported is derived from the flags in
cpufreq_table_validate_and_sort(). And then:

if (policy->cpuinfo.boost_in_table) {
    xxx;
}

> +		max_freq = enable ? policy->cpuinfo.max_table_freq :
> +				    policy->cpuinfo.max_base_freq;
> +
> +		if (!max_freq)
> +			/* when the freq table contains only boost frequencies */
> +			max_freq = policy->cpuinfo.max_table_freq;
> +	} else {
> +		max_freq = policy->cpuinfo.max_freq;
> +	}
> +
> +	ret = freq_qos_update_request(&policy->boost_freq_req, max_freq);
>   	if (ret < 0) {
>   		policy->boost_enabled = !policy->boost_enabled;
>   		cpufreq_driver->set_boost(policy, policy->boost_enabled);
> diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
> index 4984142dc08a..7e183e16162d 100644
> --- a/drivers/cpufreq/freq_table.c
> +++ b/drivers/cpufreq/freq_table.c
> @@ -34,6 +34,7 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy)
>   	unsigned int min_freq = ~0;
>   	unsigned int max_freq = 0;
>   	unsigned int max_table_freq = 0;
> +	unsigned int max_base_freq = 0;
>   	unsigned int freq, i;
>   
>   	cpufreq_for_each_valid_entry_idx(pos, table, i) {
> @@ -42,6 +43,9 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy)
>   		if (freq > max_table_freq)
>   			max_table_freq = freq;
>   
> +		if (!(pos->flags & CPUFREQ_BOOST_FREQ) && freq > max_base_freq)
> +			max_base_freq = freq;
> +
>   		if ((!cpufreq_boost_enabled() || !policy->boost_enabled)
>   		    && (pos->flags & CPUFREQ_BOOST_FREQ))
>   			continue;
> @@ -62,6 +66,7 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy)
>   		policy->cpuinfo.max_freq = max_freq;
>   
>   	policy->cpuinfo.max_table_freq = max_table_freq;
> +	policy->cpuinfo.max_base_freq = max_base_freq;
>   
>   	if (min_freq == ~0)
>   		return -EINVAL;
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 3f3b1380251a..419c71ccff7c 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -46,6 +46,7 @@ struct cpufreq_cpuinfo {
>   	unsigned int		max_freq;
>   	unsigned int		min_freq;
>   	unsigned int		max_table_freq; /* Highest valid frequency in the table */
> +	unsigned int		max_base_freq; /* Highest non-boost frequency in the table */
>   
>   	/* in 10^(-9) s = nanoseconds */
>   	unsigned int		transition_latency;


--
Thx and BRs,
Zhongqiu Han