[PATCH] ARM: dts: rockchip: Add dynamic-power-coefficient for rk3288

[PATCH] ARM: dts: rockchip: Add dynamic-power-coefficient for rk3288

[Matthias Kaehlcke]

The value was determined with the following method:

- take CPUs 1-3 offline
- for each OPP
  - set cpufreq min and max freq to OPP freq
  - start dhrystone benchmark
  - measure CPU power consumption during 10s
  - calculate Cx for OPPx
    - Cx = (Px - P1) / (Vx²fx - V1²f1)          [1]
      using the following units: mW / Ghz / V   [2]
- C = avg(C2, ..., Cn)

[1] see commit 4daa001a1773 ("arm64: dts: juno: Add cpu
     dynamic-power-coefficient information")
[2] https://patchwork.kernel.org/patch/10493615/#22158551

FTR, these are the values for the different OPPs:

freq (kHz)   	mV		Px (mW)		Cx

126000		900		39
216000		900		66		370
312000		900		95		372
408000		900		122		363
600000		900		177		359
696000		950		230		363
816000		1000		297		361
1008000		1050		404		362
1200000		1100		528		362
1416000		1200		770		377
1512000		1300		984		385
1608000		1350		1156		394

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
I couldn't find any really comprehensive information on determining
the dynamic-power-coefficient, the method used is my understanding
mostly derived from the sources mentioned above, the resulting value
is within a reasonable range and the range of the intermediate Cx
values is consistent. If someone knows better and things should be
done differently please share your knowledge :)
---
 arch/arm/boot/dts/rk3288.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/rk3288.dtsi b/arch/arm/boot/dts/rk3288.dtsi
index 23e9c5253019..f0d92b045c57 100644
--- a/arch/arm/boot/dts/rk3288.dtsi
+++ b/arch/arm/boot/dts/rk3288.dtsi
@@ -61,6 +61,7 @@
 			reg = <0x500>;
 			resets = <&cru SRST_CORE0>;
 			operating-points-v2 = <&cpu_opp_table>;
+			dynamic-power-coefficient = <370>;
 			#cooling-cells = <2>; /* min followed by max */
 			clock-latency = <40000>;
 			clocks = <&cru ARMCLK>;
@@ -71,6 +72,7 @@
 			reg = <0x501>;
 			resets = <&cru SRST_CORE1>;
 			operating-points = <&cpu_opp_table>;
+			dynamic-power-coefficient = <370>;
 			#cooling-cells = <2>; /* min followed by max */
 			clock-latency = <40000>;
 			clocks = <&cru ARMCLK>;
@@ -81,6 +83,7 @@
 			reg = <0x502>;
 			resets = <&cru SRST_CORE2>;
 			operating-points = <&cpu_opp_table>;
+			dynamic-power-coefficient = <370>;
 			#cooling-cells = <2>; /* min followed by max */
 			clock-latency = <40000>;
 			clocks = <&cru ARMCLK>;
@@ -91,6 +94,7 @@
 			reg = <0x503>;
 			resets = <&cru SRST_CORE3>;
 			operating-points = <&cpu_opp_table>;
+			dynamic-power-coefficient = <370>;
 			#cooling-cells = <2>; /* min followed by max */
 			clock-latency = <40000>;
 			clocks = <&cru ARMCLK>;
-- 
2.21.0.392.gf8f6787159e-goog

Re: [PATCH] ARM: dts: rockchip: Add dynamic-power-coefficient for rk3288

[Heiko Stübner]

Am Freitag, 12. April 2019, 02:01:58 CEST schrieb Matthias Kaehlcke:
> The value was determined with the following method:
> 
> - take CPUs 1-3 offline
> - for each OPP
>   - set cpufreq min and max freq to OPP freq
>   - start dhrystone benchmark
>   - measure CPU power consumption during 10s
>   - calculate Cx for OPPx
>     - Cx = (Px - P1) / (Vx²fx - V1²f1)          [1]
>       using the following units: mW / Ghz / V   [2]
> - C = avg(C2, ..., Cn)
> 
> [1] see commit 4daa001a1773 ("arm64: dts: juno: Add cpu
>      dynamic-power-coefficient information")
> [2] https://patchwork.kernel.org/patch/10493615/#22158551
> 
> FTR, these are the values for the different OPPs:
> 
> freq (kHz)   	mV		Px (mW)		Cx
> 
> 126000		900		39
> 216000		900		66		370
> 312000		900		95		372
> 408000		900		122		363
> 600000		900		177		359
> 696000		950		230		363
> 816000		1000		297		361
> 1008000		1050		404		362
> 1200000		1100		528		362
> 1416000		1200		770		377
> 1512000		1300		984		385
> 1608000		1350		1156		394
> 
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>

I've applied this for 5.2 but moved the new entries
below the clock properties for some more alphabetic ordering.


Heiko