Re: [PATCH v3 2/2] cpufreq: fix policy max not returning to non-boost freq on boost disable

[Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>]

On 9/29/2026 7:38 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.

I think as discussed in v2 the changelog should describe the impact of
commit 6e39ba4e5a82 ("cpufreq: Add boost_freq_req QoS request"), since
it is relevant to understanding this fix.

> Later commit db80ad776cd2 ("cpufreq: Remove driver default policy->min/max
> init") dropped the 'policy->max = max_freq' assignment from
> cpufreq_frequency_table_cpuinfo, leaving that one-way-guard to be the only
> path for cpuinfo max and consequently policy max to be updated, causing
> both values 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. If boost frequencies are available, use the highest
> frequency from the table/max_base_freq instead of cpuinfo->max_freq to
> control boost values, so the value can decrease again when boost is
> disabled.
> 
> Fixes: db80ad776cd2 ("cpufreq: Remove driver default policy->min/max init")

Patch 2/2 currently depends on a helper introduced by patch 1/2, which
prevents it from being backported independently. Since 2/2 is an
independent fix that should be backported to stable on its own, I think
it should be placed before patch 1/2 in the series and kept self
contained.

> Signed-off-by: Ananthu C V <ananthu.cv@oss.qualcomm.com>
> ---
>   drivers/cpufreq/cpufreq.c    | 16 +++++++++++++++-
>   drivers/cpufreq/freq_table.c |  9 ++++++++-
>   include/linux/cpufreq.h      |  3 +++
>   3 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 96515880b4ac..5e6afb6f8826 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -574,6 +574,8 @@ 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;
> +	unsigned int max_table_freq;
>   	int ret;
>   
>   	if (policy->boost_enabled == enable)
> @@ -587,7 +589,19 @@ 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);
> +	max_table_freq = cpufreq_frequency_table_max(policy);
> +
> +	if (policy_has_boost_freq(policy)) {
> +		max_freq = enable ? max_table_freq : policy->cpuinfo.max_base_freq;
> +
> +		if (!max_freq)
> +			/* when the freq table contains only boost frequencies */
> +			max_freq = 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 ea994647abc8..820ed4559f6c 100644
> --- a/drivers/cpufreq/freq_table.c
> +++ b/drivers/cpufreq/freq_table.c
> @@ -14,7 +14,7 @@
>    *                     FREQUENCY TABLE HELPERS                       *
>    *********************************************************************/
>   
> -static bool policy_has_boost_freq(struct cpufreq_policy *policy)
> +bool policy_has_boost_freq(struct cpufreq_policy *policy)
>   {
>   	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
>   
> @@ -27,17 +27,22 @@ static bool policy_has_boost_freq(struct cpufreq_policy *policy)
>   
>   	return false;
>   }
> +EXPORT_SYMBOL_GPL(policy_has_boost_freq);
>   
>   int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy)
>   {
>   	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
>   	unsigned int min_freq = ~0;
>   	unsigned int max_freq = 0;
> +	unsigned int max_base_freq = 0;
>   	unsigned int freq, i;
>   
>   	cpufreq_for_each_valid_entry_idx(pos, table, i) {
>   		freq = pos->frequency;
>   
> +		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;
> @@ -57,6 +62,8 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy)
>   	if (policy->cpuinfo.max_freq < max_freq)
>   		policy->cpuinfo.max_freq = max_freq;
>   
> +	policy->cpuinfo.max_base_freq = max_base_freq;
> +
>   	if (min_freq == ~0)
>   		return -EINVAL;
>   	else
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index f048c925fd98..7bb58405e004 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -45,6 +45,7 @@ enum cpufreq_table_sorting {
>   struct cpufreq_cpuinfo {
>   	unsigned int		max_freq;
>   	unsigned int		min_freq;
> +	unsigned int		max_base_freq; /* Highest non-boost frequency in the table */


To avoid introducing a new member that is only used by frequency-table
drivers, please consider the following implementation instead:

If there are boost entries in the frequency table, the table is the only
source of cpuinfo.max_freq, so let cpufreq_frequency_table_cpuinfo() set
it unconditionally in that case.


diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index ea99464..8c8bad2 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c
@@ -33,14 +33,17 @@ int cpufreq_frequency_table_cpuinfo(struct 
cpufreq_policy *policy)
  	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
  	unsigned int min_freq = ~0;
  	unsigned int max_freq = 0;
+	bool has_boost = false;
  	unsigned int freq, i;

  	cpufreq_for_each_valid_entry_idx(pos, table, i) {
  		freq = pos->frequency;

-		if ((!cpufreq_boost_enabled() || !policy->boost_enabled)
-		    && (pos->flags & CPUFREQ_BOOST_FREQ))
-			continue;
+		if (pos->flags & CPUFREQ_BOOST_FREQ) {
+			has_boost = true;
+			if (!cpufreq_boost_enabled() || !policy->boost_enabled)
+				continue;
+		}

  		pr_debug("table entry %u: %u kHz\n", i, freq);
  		if (freq < min_freq)
@@ -50,17 +53,20 @@ int cpufreq_frequency_table_cpuinfo(struct 
cpufreq_policy *policy)
  	}

  	policy->cpuinfo.min_freq = min_freq;
+
+	if (min_freq == ~0)
+		return -EINVAL;
+
  	/*
  	 * If the driver has set its own cpuinfo.max_freq above max_freq, leave
-	 * it as is.
+	 * it as is.  This does not apply to tables with boost entries, because
+	 * the table is the only source of cpuinfo.max_freq then and it needs
+	 * to go down again when boost is disabled.
  	 */
-	if (policy->cpuinfo.max_freq < max_freq)
+	if (has_boost || policy->cpuinfo.max_freq < max_freq)
  		policy->cpuinfo.max_freq = max_freq;

-	if (min_freq == ~0)
-		return -EINVAL;
-	else
-		return 0;
+	return 0;
  }

  int cpufreq_frequency_table_verify(struct cpufreq_policy_data *policy)


>   
>   	/* in 10^(-9) s = nanoseconds */
>   	unsigned int		transition_latency;
> @@ -791,6 +792,8 @@ struct cpufreq_frequency_table {
>   
>   int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy);
>   
> +bool policy_has_boost_freq(struct cpufreq_policy *policy);
> +
>   int cpufreq_frequency_table_verify(struct cpufreq_policy_data *policy);
>   
>   int cpufreq_generic_frequency_table_verify(struct cpufreq_policy_data *policy);
> 


-- 
Thx and BRs,
Zhongqiu Han