linux-kernel - [PATCH 1/2] ARM: dts: exynos: Add dynamic-power-coefficient to Exynos5422 CPUs

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Message-Id: <20200219095828.8063-2-lukasz.luba@arm.com>
Date:   Wed, 19 Feb 2020 09:58:27 +0000
From:   lukasz.luba@....com
To:     kgene@...nel.org, krzk@...nel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        cw00.choi@...sung.com, robh+dt@...nel.org, mark.rutland@....com,
        b.zolnierkie@...sung.com, lukasz.luba@....com,
        dietmar.eggemann@....com
Subject: [PATCH 1/2] ARM: dts: exynos: Add dynamic-power-coefficient to Exynos5422 CPUs

From: Lukasz Luba <lukasz.luba@....com>

To use Energy Aware Scheduler (EAS) the Energy Model (EM) should be
registered for CPUs. Add dynamic-power-coefficient into CPU nodes which
let CPUFreq subsystem register the EM structures. This will increase
energy efficiency of big.LITTLE platforms.

The 'dynamic-power-coefficient' values have been obtained experimenting
with different workloads. The power measurements taken from big CPU
Cluster and LITTLE CPU Cluster has been compared with official documents
and synthetic workloads estimations. The effective power ratio between
Cortex-A7 and Cortex-A15 CPUs (~3x) is also aligned with documentation.

Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 arch/arm/boot/dts/exynos5422-cpus.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm/boot/dts/exynos5422-cpus.dtsi b/arch/arm/boot/dts/exynos5422-cpus.dtsi
index 1b8605cf2407..4b641b9b8179 100644
--- a/arch/arm/boot/dts/exynos5422-cpus.dtsi
+++ b/arch/arm/boot/dts/exynos5422-cpus.dtsi
@@ -31,6 +31,7 @@
 			operating-points-v2 = <&cluster_a7_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
 			capacity-dmips-mhz = <539>;
+			dynamic-power-coefficient = <90>;
 		};
 
 		cpu1: cpu@101 {
@@ -43,6 +44,7 @@
 			operating-points-v2 = <&cluster_a7_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
 			capacity-dmips-mhz = <539>;
+			dynamic-power-coefficient = <90>;
 		};
 
 		cpu2: cpu@102 {
@@ -55,6 +57,7 @@
 			operating-points-v2 = <&cluster_a7_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
 			capacity-dmips-mhz = <539>;
+			dynamic-power-coefficient = <90>;
 		};
 
 		cpu3: cpu@103 {
@@ -67,6 +70,7 @@
 			operating-points-v2 = <&cluster_a7_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
 			capacity-dmips-mhz = <539>;
+			dynamic-power-coefficient = <90>;
 		};
 
 		cpu4: cpu@0 {
@@ -79,6 +83,7 @@
 			operating-points-v2 = <&cluster_a15_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
 			capacity-dmips-mhz = <1024>;
+			dynamic-power-coefficient = <310>;
 		};
 
 		cpu5: cpu@1 {
@@ -91,6 +96,7 @@
 			operating-points-v2 = <&cluster_a15_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
 			capacity-dmips-mhz = <1024>;
+			dynamic-power-coefficient = <310>;
 		};
 
 		cpu6: cpu@2 {
@@ -103,6 +109,7 @@
 			operating-points-v2 = <&cluster_a15_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
 			capacity-dmips-mhz = <1024>;
+			dynamic-power-coefficient = <310>;
 		};
 
 		cpu7: cpu@3 {
@@ -115,6 +122,7 @@
 			operating-points-v2 = <&cluster_a15_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
 			capacity-dmips-mhz = <1024>;
+			dynamic-power-coefficient = <310>;
 		};
 	};
 };
-- 
2.17.1