diff mbox series

arm64: dts: mediatek: mt8192: Fix CPUs capacity-dmips-mhz

Message ID 20230602183515.3778780-1-nfraprado@collabora.com
State Accepted
Commit a4366b5695c984b8a3fc8b31de9e758c8f6d1aed
Headers show
Series arm64: dts: mediatek: mt8192: Fix CPUs capacity-dmips-mhz | expand

Commit Message

NĂ­colas F. R. A. Prado June 2, 2023, 6:35 p.m. UTC
The capacity-dmips-mhz parameter was miscalculated: this SoC runs
the first (Cortex-A55) cluster at a maximum of 2000MHz and the
second (Cortex-A76) cluster at a maximum of 2200MHz.

In order to calculate the right capacity-dmips-mhz, the following
test was performed:
1. CPUFREQ governor was set to 'performance' on both clusters
2. Ran dhrystone with 500000000 iterations for 10 times on each cluster
3. Calculated the mean result for each cluster
4. Calculated DMIPS/MHz: dmips_mhz = dmips_per_second / cpu_mhz
5. Scaled results to 1024:
   result_c0 = dmips_mhz_c0 / dmips_mhz_c1 * 1024

The mean results for this SoC are:
Cluster 0 (LITTLE): 12016411 Dhry/s
Cluster 1 (BIG): 31702034 Dhry/s

The calculated scaled results are:
Cluster 0: 426.953226899238 (rounded to 427)
Cluster 1: 1024

Fixes: 48489980e27e ("arm64: dts: Add Mediatek SoC MT8192 and evaluation board dts and Makefile")
Signed-off-by: NĂ­colas F. R. A. Prado <nfraprado@collabora.com>

---

 arch/arm64/boot/dts/mediatek/mt8192.dtsi | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/arch/arm64/boot/dts/mediatek/mt8192.dtsi b/arch/arm64/boot/dts/mediatek/mt8192.dtsi
index 63247c832f42..db17f67bb801 100644
--- a/arch/arm64/boot/dts/mediatek/mt8192.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8192.dtsi
@@ -71,7 +71,7 @@  cpu0: cpu@0 {
 			d-cache-sets = <128>;
 			next-level-cache = <&l2_0>;
 			performance-domains = <&performance 0>;
-			capacity-dmips-mhz = <530>;
+			capacity-dmips-mhz = <427>;
 		};
 
 		cpu1: cpu@100 {
@@ -89,7 +89,7 @@  cpu1: cpu@100 {
 			d-cache-sets = <128>;
 			next-level-cache = <&l2_0>;
 			performance-domains = <&performance 0>;
-			capacity-dmips-mhz = <530>;
+			capacity-dmips-mhz = <427>;
 		};
 
 		cpu2: cpu@200 {
@@ -107,7 +107,7 @@  cpu2: cpu@200 {
 			d-cache-sets = <128>;
 			next-level-cache = <&l2_0>;
 			performance-domains = <&performance 0>;
-			capacity-dmips-mhz = <530>;
+			capacity-dmips-mhz = <427>;
 		};
 
 		cpu3: cpu@300 {
@@ -125,7 +125,7 @@  cpu3: cpu@300 {
 			d-cache-sets = <128>;
 			next-level-cache = <&l2_0>;
 			performance-domains = <&performance 0>;
-			capacity-dmips-mhz = <530>;
+			capacity-dmips-mhz = <427>;
 		};
 
 		cpu4: cpu@400 {