linux-kernel - [[PATCH 2/8] PM: EM: Add artificial EM flag

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Date:   Wed, 16 Mar 2022 23:52:05 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     linux-kernel@...r.kernel.org
Cc:     lukasz.luba@....com, dietmar.eggemann@....com,
        Pierre.Gondois@....com, ionela.voinescu@....com,
        viresh.kumar@...aro.org, rafael@...nel.org,
        daniel.lezcano@...aro.org, linux-pm@...r.kernel.org,
        mka@...omium.org, nm@...com, sboyd@...nel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, cristian.marussi@....com,
        sudeep.holla@....com, matthias.bgg@...il.com
Subject: [[PATCH 2/8] PM: EM: Add artificial EM flag

From: Pierre Gondois <Pierre.Gondois@....com>

The Energy Model (EM) can be used on platforms which are missing real
power information. Those platforms would implement .get_cost() which
populates needed values for the Energy Aware Scheduler (EAS). The EAS
doesn't use 'power' fields from EM, but other frameworks might use them.
Thus, to avoid miss-usage of this specific type of EM, introduce a new
flags which can be checked by other frameworks.

Signed-off-by: Pierre Gondois <Pierre.Gondois@....com>
Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 include/linux/energy_model.h | 5 +++++
 kernel/power/energy_model.c  | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index 0a3a5663177b..92e82a322859 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -67,11 +67,16 @@ struct em_perf_domain {
  *
  *  EM_PERF_DOMAIN_SKIP_INEFFICIENCIES: Skip inefficient states when estimating
  *  energy consumption.
+ *
+ *  EM_PERF_DOMAIN_ARTIFICIAL: The power values are artificial and might be
+ *  created by platform missing real power information
  */
 #define EM_PERF_DOMAIN_MILLIWATTS BIT(0)
 #define EM_PERF_DOMAIN_SKIP_INEFFICIENCIES BIT(1)
+#define EM_PERF_DOMAIN_ARTIFICIAL BIT(2)
 
 #define em_span_cpus(em) (to_cpumask((em)->cpus))
+#define em_is_artificial(em) ((em)->flags & EM_PERF_DOMAIN_ARTIFICIAL)
 
 #ifdef CONFIG_ENERGY_MODEL
 #define EM_MAX_POWER 0xFFFF
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 0153b0ca7b23..6ecee99af842 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -384,6 +384,8 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
 
 	if (milliwatts)
 		dev->em_pd->flags |= EM_PERF_DOMAIN_MILLIWATTS;
+	else if (cb->get_cost)
+		dev->em_pd->flags |= EM_PERF_DOMAIN_ARTIFICIAL;
 
 	em_cpufreq_update_efficiencies(dev);
 
-- 
2.17.1