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From: Lukasz Luba <lukasz.luba@arm.com>
To: linux-kernel@vger.kernel.org,
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Subject: [PATCH v8 17/23] powercap/dtpm_devfreq: Use new Energy Model interface to get table
Date: Thu,  8 Feb 2024 11:55:51 +0000
Message-Id: <20240208115557.1273962-18-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_devfreq.c | 34 ++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/drivers/powercap/dtpm_devfreq.c b/drivers/powercap/dtpm_devfreq.c
index 612c3b59dd5b..f40bce8176df 100644
--- a/drivers/powercap/dtpm_devfreq.c
+++ b/drivers/powercap/dtpm_devfreq.c
@@ -37,11 +37,16 @@ static int update_pd_power_uw(struct dtpm *dtpm)
 	struct devfreq *devfreq = dtpm_devfreq->devfreq;
 	struct device *dev = devfreq->dev.parent;
 	struct em_perf_domain *pd = em_pd_get(dev);
+	struct em_perf_state *table;
 
-	dtpm->power_min = pd->table[0].power;
+	rcu_read_lock();
+	table = em_perf_state_from_pd(pd);
 
-	dtpm->power_max = pd->table[pd->nr_perf_states - 1].power;
+	dtpm->power_min = table[0].power;
 
+	dtpm->power_max = table[pd->nr_perf_states - 1].power;
+
+	rcu_read_unlock();
 	return 0;
 }
 
@@ -51,20 +56,23 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
 	struct devfreq *devfreq = dtpm_devfreq->devfreq;
 	struct device *dev = devfreq->dev.parent;
 	struct em_perf_domain *pd = em_pd_get(dev);
+	struct em_perf_state *table;
 	unsigned long freq;
 	int i;
 
+	rcu_read_lock();
+	table = em_perf_state_from_pd(pd);
 	for (i = 0; i < pd->nr_perf_states; i++) {
-		if (pd->table[i].power > power_limit)
+		if (table[i].power > power_limit)
 			break;
 	}
 
-	freq = pd->table[i - 1].frequency;
+	freq = table[i - 1].frequency;
+	power_limit = table[i - 1].power;
+	rcu_read_unlock();
 
 	dev_pm_qos_update_request(&dtpm_devfreq->qos_req, freq);
 
-	power_limit = pd->table[i - 1].power;
-
 	return power_limit;
 }
 
@@ -89,8 +97,9 @@ static u64 get_pd_power_uw(struct dtpm *dtpm)
 	struct device *dev = devfreq->dev.parent;
 	struct em_perf_domain *pd = em_pd_get(dev);
 	struct devfreq_dev_status status;
+	struct em_perf_state *table;
 	unsigned long freq;
-	u64 power;
+	u64 power = 0;
 	int i;
 
 	mutex_lock(&devfreq->lock);
@@ -100,19 +109,22 @@ static u64 get_pd_power_uw(struct dtpm *dtpm)
 	freq = DIV_ROUND_UP(status.current_frequency, HZ_PER_KHZ);
 	_normalize_load(&status);
 
+	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;
 
-		power = pd->table[i].power;
+		power = table[i].power;
 		power *= status.busy_time;
 		power >>= 10;
 
-		return power;
+		break;
 	}
+	rcu_read_unlock();
 
-	return 0;
+	return power;
 }
 
 static void pd_release(struct dtpm *dtpm)
-- 
2.25.1