[PATCH 6.0 0060/1073] arm64: dts: mediatek: mt8195: Fix CPUs capacity-dmips-mhz

Greg Kroah-Hartman
2022-12-28T15:01:18Z

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

[ Upstream commit 513c43328b189874fdfee3ae99cac81e5502e7f7 ]

The capacity-dmips-mhz parameter was miscalculated: this SoC runs
the first (Cortex-A55) cluster at a maximum of 2000MHz and the
second (Cortex-A78) cluster at a maximum of 3000MHz.

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. Calculate the mean result for each cluster
4. Calculate DMIPS/MHz: dmips_mhz = dmips_per_second / cpu_mhz
5. Scale results to 1024:
result_c0 = (dmips_mhz_c0 - min_dmips_mhz(c0, c1)) /
(max_dmips_mhz(c0, c1) - min_dmips_mhz(c0, c1)) * 1024

The mean results for this SoC are:
Cluster 0 (LITTLE): 11990400 Dhry/s
Cluster 1 (BIG): 59809036 Dhry/s

The calculated scaled results are:
Cluster 0: 307,934312801831 (rounded to 308)
Cluster 1: 1024

Fixes: 37f2582883be ("arm64: dts: Add mediatek SoC mt8195 and evaluation board")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20221005093404.33102-1-angelogioacchino.delregno@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/boot/dts/mediatek/mt8195.dtsi | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/boot/dts/mediatek/mt8195.dtsi b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
index 066c14989708..e694ddb74f7d 100644
--- a/arch/arm64/boot/dts/mediatek/mt8195.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
@@ -27,7 +27,7 @@ cpu0: cpu@0 {
reg = <0x000>;
enable-method = "psci";
clock-frequency = <1701000000>;
- capacity-dmips-mhz = <578>;
+ capacity-dmips-mhz = <308>;
cpu-idle-states = <&cpu_off_l &cluster_off_l>;
next-level-cache = <&l2_0>;
#cooling-cells = <2>;
@@ -39,7 +39,7 @@ cpu1: cpu@100 {
reg = <0x100>;
enable-method = "psci";
clock-frequency = <1701000000>;
- capacity-dmips-mhz = <578>;
+ capacity-dmips-mhz = <308>;
cpu-idle-states = <&cpu_off_l &cluster_off_l>;
next-level-cache = <&l2_0>;
#cooling-cells = <2>;
@@ -51,7 +51,7 @@ cpu2: cpu@200 {
reg = <0x200>;
enable-method = "psci";
clock-frequency = <1701000000>;
- capacity-dmips-mhz = <578>;
+ capacity-dmips-mhz = <308>;
cpu-idle-states = <&cpu_off_l &cluster_off_l>;
next-level-cache = <&l2_0>;
#cooling-cells = <2>;
@@ -63,7 +63,7 @@ cpu3: cpu@300 {
reg = <0x300>;
enable-method = "psci";
clock-frequency = <1701000000>;
- capacity-dmips-mhz = <578>;
+ capacity-dmips-mhz = <308>;
cpu-idle-states = <&cpu_off_l &cluster_off_l>;
next-level-cache = <&l2_0>;
#cooling-cells = <2>;
--
2.35.1