linux-kernel - [PATCH] arm64: dts: hisilicon: Add hi3660 cpu capacity-dmips-mhz information

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Date:   Wed, 13 Dec 2017 14:21:06 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Wei Xu <xuwei5@...ilicon.com>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org
Subject: [PATCH] arm64: dts: hisilicon: Add hi3660 cpu capacity-dmips-mhz information

The following dt entries are added:
 cpus [0-3] (Cortex A53):
   - capacity-dmips-mhz = <592>;

 cpus [4-7] (Cortex A73):
   - capacity-dmips-mhz = <1024>;

Those values were obtained by running dhrystone 2.1 on a
HiKey960 with the following procedure:
- Offline all CPUs but CPU0 (A53)
- Set CPU0 frequency to maximum
- Run Dhrystone 2.1 for 20 seconds

- Offline all CPUs but CPU4 (A73)
- set CPU4 frequency to maximum
- Run Dhrystone 2.1 for 20 seconds

The results are as follows:
A53: 129633887 loops
A73: 287034147 loops

By scaling those values so that the A73s use 1024, we end up with 462
for the A53s. However, they have different maximum frequencies:
1.844GHz for A53s and 2.362GHz for A73s. Thus, we can scale the A53
value to truly represent dmips per MHz, and we end up with 592.

The impact of this change can be verified on HiKey960:

$ cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq
1844000
1844000
1844000
1844000
2362000
2362000
2362000
2362000

$ cat /sys/devices/system/cpu/cpu*/cpu_capacity
462
462
462
462
1024
1024
1024
1024

Signed-off-by: Valentin Schneider <valentin.schneider@....com>
---
 arch/arm64/boot/dts/hisilicon/hi3660.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/hisilicon/hi3660.dtsi b/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
index ab0b95b..04a8d28 100644
--- a/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
+++ b/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
@@ -61,6 +61,7 @@
 			enable-method = "psci";
 			next-level-cache = <&A53_L2>;
 			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP_0>;
+			capacity-dmips-mhz = <592>;
 		};
 
 		cpu1: cpu@1 {
@@ -70,6 +71,7 @@
 			enable-method = "psci";
 			next-level-cache = <&A53_L2>;
 			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP_0>;
+			capacity-dmips-mhz = <592>;
 		};
 
 		cpu2: cpu@2 {
@@ -79,6 +81,7 @@
 			enable-method = "psci";
 			next-level-cache = <&A53_L2>;
 			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP_0>;
+			capacity-dmips-mhz = <592>;
 		};
 
 		cpu3: cpu@3 {
@@ -88,6 +91,7 @@
 			enable-method = "psci";
 			next-level-cache = <&A53_L2>;
 			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP_0>;
+			capacity-dmips-mhz = <592>;
 		};
 
 		cpu4: cpu@100 {
@@ -101,6 +105,7 @@
 					&CPU_SLEEP
 					&CLUSTER_SLEEP_1
 			>;
+			capacity-dmips-mhz = <1024>;
 		};
 
 		cpu5: cpu@101 {
@@ -114,6 +119,7 @@
 					&CPU_SLEEP
 					&CLUSTER_SLEEP_1
 			>;
+			capacity-dmips-mhz = <1024>;
 		};
 
 		cpu6: cpu@102 {
@@ -127,6 +133,7 @@
 					&CPU_SLEEP
 					&CLUSTER_SLEEP_1
 			>;
+			capacity-dmips-mhz = <1024>;
 		};
 
 		cpu7: cpu@103 {
@@ -140,6 +147,7 @@
 					&CPU_SLEEP
 					&CLUSTER_SLEEP_1
 			>;
+			capacity-dmips-mhz = <1024>;
 		};
 
 		idle-states {
--
2.7.4