linux-kernel - [PATCH v1 2/4] cpufreq: Add boost_freq

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Message-ID: <20251204101344.192678-3-pierre.gondois@arm.com>
Date: Thu,  4 Dec 2025 11:13:38 +0100
From: Pierre Gondois <pierre.gondois@....com>
To: linux-kernel@...r.kernel.org
Cc: Christian Loehle <christian.loehle@....com>,
	Ionela Voinescu <ionela.voinescu@....com>,
	zhenglifeng1@...wei.com,
	Jie Zhan <zhanjie9@...ilicon.com>,
	Pierre Gondois <pierre.gondois@....com>,
	Huang Rui <ray.huang@....com>,
	"Gautham R. Shenoy" <gautham.shenoy@....com>,
	Mario Limonciello <mario.limonciello@....com>,
	Perry Yuan <perry.yuan@....com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	linux-pm@...r.kernel.org
Subject: [PATCH v1 2/4] cpufreq: Add boost_freq_req QoS request

The Power Management Quality of Service (PM QoS) allows to
aggregate constraints from multiple entities. It is currently
used to manage the min/max frequency of a given policy.

Frequency constraints can come for instance from:
- Thermal framework: acpi_thermal_cpufreq_init()
- Firmware: _PPC objects: acpi_processor_ppc_init()
- User: by setting policyX/scaling_[min|max]_freq
The minimum of the max frequency constraints is used to compute
the resulting maximum allowed frequency.

When enabling boost frequencies, the same frequency request object
(policy->max_freq_req) as to handle requests from users is used.
As a result, when setting:
- scaling_max_freq
- boost
The last sysfs file used overwrites the request from the other
sysfs file.

To avoid this, create a per-policy boost_freq_req to save the boost
constraints instead of overwriting the last scaling_max_freq
constraint.

Signed-off-by: Pierre Gondois <pierre.gondois@....com>
---
 drivers/cpufreq/cpufreq.c | 35 +++++++++++++++++++++++++++++++++++
 include/linux/cpufreq.h   |  1 +
 2 files changed, 36 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 11b29c7dbea9e..23f64346b80f8 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1370,6 +1370,18 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
 		freq_qos_remove_request(policy->max_freq_req);
 	}
 
+	if (policy->boost_freq_req) {
+		/*
+		 * Remove boost_freq_req after sending CPUFREQ_REMOVE_POLICY
+		 * notification, since CPUFREQ_CREATE_POLICY notification was
+		 * sent after adding boost_freq_req earlier.
+		 */
+		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+					     CPUFREQ_REMOVE_POLICY, policy);
+		freq_qos_remove_request(policy->boost_freq_req);
+		kfree(policy->boost_freq_req);
+	}
+
 	freq_qos_remove_request(policy->min_freq_req);
 	kfree(policy->min_freq_req);
 
@@ -1476,6 +1488,29 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy,
 			goto out_destroy_policy;
 		}
 
+		if (policy->boost_supported) {
+			policy->boost_freq_req = kzalloc(sizeof(*policy->boost_freq_req),
+				GFP_KERNEL);
+			if (!policy->boost_freq_req) {
+				ret = -ENOMEM;
+				goto out_destroy_policy;
+			}
+
+			ret = freq_qos_add_request(&policy->constraints,
+						   policy->boost_freq_req,
+						   FREQ_QOS_MAX,
+						   FREQ_QOS_MAX_DEFAULT_VALUE);
+			if (ret < 0) {
+				/*
+				 * So we don't call freq_qos_remove_request() for an
+				 * uninitialized request.
+				 */
+				kfree(policy->boost_freq_req);
+				policy->boost_freq_req = NULL;
+				goto out_destroy_policy;
+			}
+		}
+
 		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
 				CPUFREQ_CREATE_POLICY, policy);
 	}
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 0465d1e6f72ac..c292a6a19e4f5 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -81,6 +81,7 @@ struct cpufreq_policy {
 	struct freq_constraints	constraints;
 	struct freq_qos_request	*min_freq_req;
 	struct freq_qos_request	*max_freq_req;
+	struct freq_qos_request *boost_freq_req;
 
 	struct cpufreq_frequency_table	*freq_table;
 	enum cpufreq_table_sorting freq_table_sorted;
-- 
2.43.0