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From: Lukasz Luba <lukasz.luba@arm.com>
To: linux-kernel@vger.kernel.org,
	linux-pm@vger.kernel.org,
	rafael@kernel.org
Cc: lukasz.luba@arm.com,
	dietmar.eggemann@arm.com,
	rui.zhang@intel.com,
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	amit.kachhap@gmail.com,
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	viresh.kumar@linaro.org,
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	mhiramat@kernel.org,
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Subject: [PATCH v8 16/23] powercap/dtpm_cpu: Use new Energy Model interface to get table
Date: Thu,  8 Feb 2024 11:55:50 +0000
Message-Id: <20240208115557.1273962-17-lukasz.luba@arm.com>
In-Reply-To: <20240208115557.1273962-1-lukasz.luba@arm.com>
References: <20240208115557.1273962-1-lukasz.luba@arm.com>
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Energy Model framework support modifications at runtime of the power
values. Use the new EM table API which is protected with RCU. Align the
code so that this RCU read section is short.

This change is not expected to alter the general functionality.

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 drivers/powercap/dtpm_cpu.c | 39 +++++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
index 9193c3b8edeb..ee0d1aa3e023 100644
--- a/drivers/powercap/dtpm_cpu.c
+++ b/drivers/powercap/dtpm_cpu.c
@@ -42,6 +42,7 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
 {
 	struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 	struct em_perf_domain *pd = em_cpu_get(dtpm_cpu->cpu);
+	struct em_perf_state *table;
 	struct cpumask cpus;
 	unsigned long freq;
 	u64 power;
@@ -50,20 +51,22 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
 	cpumask_and(&cpus, cpu_online_mask, to_cpumask(pd->cpus));
 	nr_cpus = cpumask_weight(&cpus);
 
+	rcu_read_lock();
+	table = em_perf_state_from_pd(pd);
 	for (i = 0; i < pd->nr_perf_states; i++) {
 
-		power = pd->table[i].power * nr_cpus;
+		power = table[i].power * nr_cpus;
 
 		if (power > power_limit)
 			break;
 	}
 
-	freq = pd->table[i - 1].frequency;
+	freq = table[i - 1].frequency;
+	power_limit = table[i - 1].power * nr_cpus;
+	rcu_read_unlock();
 
 	freq_qos_update_request(&dtpm_cpu->qos_req, freq);
 
-	power_limit = pd->table[i - 1].power * nr_cpus;
-
 	return power_limit;
 }
 
@@ -87,9 +90,11 @@ static u64 scale_pd_power_uw(struct cpumask *pd_mask, u64 power)
 static u64 get_pd_power_uw(struct dtpm *dtpm)
 {
 	struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
+	struct em_perf_state *table;
 	struct em_perf_domain *pd;
 	struct cpumask *pd_mask;
 	unsigned long freq;
+	u64 power = 0;
 	int i;
 
 	pd = em_cpu_get(dtpm_cpu->cpu);
@@ -98,33 +103,43 @@ static u64 get_pd_power_uw(struct dtpm *dtpm)
 
 	freq = cpufreq_quick_get(dtpm_cpu->cpu);
 
+	rcu_read_lock();
+	table = em_perf_state_from_pd(pd);
 	for (i = 0; i < pd->nr_perf_states; i++) {
 
-		if (pd->table[i].frequency < freq)
+		if (table[i].frequency < freq)
 			continue;
 
-		return scale_pd_power_uw(pd_mask, pd->table[i].power);
+		power = scale_pd_power_uw(pd_mask, table[i].power);
+		break;
 	}
+	rcu_read_unlock();
 
-	return 0;
+	return power;
 }
 
 static int update_pd_power_uw(struct dtpm *dtpm)
 {
 	struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 	struct em_perf_domain *em = em_cpu_get(dtpm_cpu->cpu);
+	struct em_perf_state *table;
 	struct cpumask cpus;
 	int nr_cpus;
 
 	cpumask_and(&cpus, cpu_online_mask, to_cpumask(em->cpus));
 	nr_cpus = cpumask_weight(&cpus);
 
-	dtpm->power_min = em->table[0].power;
+	rcu_read_lock();
+	table = em_perf_state_from_pd(em);
+
+	dtpm->power_min = table[0].power;
 	dtpm->power_min *= nr_cpus;
 
-	dtpm->power_max = em->table[em->nr_perf_states - 1].power;
+	dtpm->power_max = table[em->nr_perf_states - 1].power;
 	dtpm->power_max *= nr_cpus;
 
+	rcu_read_unlock();
+
 	return 0;
 }
 
@@ -180,6 +195,7 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
 {
 	struct dtpm_cpu *dtpm_cpu;
 	struct cpufreq_policy *policy;
+	struct em_perf_state *table;
 	struct em_perf_domain *pd;
 	char name[CPUFREQ_NAME_LEN];
 	int ret = -ENOMEM;
@@ -216,9 +232,12 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
 	if (ret)
 		goto out_kfree_dtpm_cpu;
 
+	rcu_read_lock();
+	table = em_perf_state_from_pd(pd);
 	ret = freq_qos_add_request(&policy->constraints,
 				   &dtpm_cpu->qos_req, FREQ_QOS_MAX,
-				   pd->table[pd->nr_perf_states - 1].frequency);
+				   table[pd->nr_perf_states - 1].frequency);
+	rcu_read_unlock();
 	if (ret)
 		goto out_dtpm_unregister;
 
-- 
2.25.1