The capacitance value is required for the usage of the cpufreq cooling
device and power_allocator thermal governor in the appropriate energy
model.
It helps to compute the power estimated by the SoC at the appropriate
frequency. If it is the frequency of an existing OPP, or at the
frequency of the first OPP above the requested value otherwise.
The power is estimated as P = C * V^2 * f, with C being the SoC's
capacitance and V and f respectively representing the voltage and
frequency of the OPP.
Since AXG SoC doesn't have SCMI protocol support, we need to initialize
capacitance using the 'dynamic-power-coefficient' DT entry. Its value is
retrieved from the vendor kernel, and it gives us the following
freq2power mapping:
+-----------+--------+
| frequency,| power, |
| MHz | uW |
+-----------+--------+
| 100 | 10354 |
+-----------+--------+
| 250 | 27104 |
+-----------+--------+
| 500 | 55447 |
+-----------+--------+
| 667 | 77327 |
+-----------+--------+
| 1000 | 129024 |
+-----------+--------+
| 1200 | 164656 |
+-----------+--------+
| 1296 | 192489 |
+-----------+--------+
| 1416 | 239870 |
+-----------+--------+
Signed-off-by: Dmitry Rokosov <[email protected]>
---
arch/arm64/boot/dts/amlogic/meson-axg.dtsi | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm64/boot/dts/amlogic/meson-axg.dtsi b/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
index ea96fef328e8..6d12b760b90f 100644
--- a/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
@@ -74,6 +74,7 @@ cpu0: cpu@0 {
enable-method = "psci";
next-level-cache = <&l2>;
clocks = <&scpi_dvfs 0>;
+ dynamic-power-coefficient = <140>;
#cooling-cells = <2>;
};
@@ -84,6 +85,7 @@ cpu1: cpu@1 {
enable-method = "psci";
next-level-cache = <&l2>;
clocks = <&scpi_dvfs 0>;
+ dynamic-power-coefficient = <140>;
#cooling-cells = <2>;
};
@@ -94,6 +96,7 @@ cpu2: cpu@2 {
enable-method = "psci";
next-level-cache = <&l2>;
clocks = <&scpi_dvfs 0>;
+ dynamic-power-coefficient = <140>;
#cooling-cells = <2>;
};
@@ -104,6 +107,7 @@ cpu3: cpu@3 {
enable-method = "psci";
next-level-cache = <&l2>;
clocks = <&scpi_dvfs 0>;
+ dynamic-power-coefficient = <140>;
#cooling-cells = <2>;
};
--
2.43.0
On 09/02/2024 22:28, Dmitry Rokosov wrote:
> The capacitance value is required for the usage of the cpufreq cooling
> device and power_allocator thermal governor in the appropriate energy
> model.
>
> It helps to compute the power estimated by the SoC at the appropriate
> frequency. If it is the frequency of an existing OPP, or at the
> frequency of the first OPP above the requested value otherwise.
>
> The power is estimated as P = C * V^2 * f, with C being the SoC's
> capacitance and V and f respectively representing the voltage and
> frequency of the OPP.
>
> Since AXG SoC doesn't have SCMI protocol support, we need to initialize
> capacitance using the 'dynamic-power-coefficient' DT entry. Its value is
> retrieved from the vendor kernel, and it gives us the following
> freq2power mapping:
> +-----------+--------+
> | frequency,| power, |
> | MHz | uW |
> +-----------+--------+
> | 100 | 10354 |
> +-----------+--------+
> | 250 | 27104 |
> +-----------+--------+
> | 500 | 55447 |
> +-----------+--------+
> | 667 | 77327 |
> +-----------+--------+
> | 1000 | 129024 |
> +-----------+--------+
> | 1200 | 164656 |
> +-----------+--------+
> | 1296 | 192489 |
> +-----------+--------+
> | 1416 | 239870 |
> +-----------+--------+
>
> Signed-off-by: Dmitry Rokosov <[email protected]>
> ---
> arch/arm64/boot/dts/amlogic/meson-axg.dtsi | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/amlogic/meson-axg.dtsi b/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> index ea96fef328e8..6d12b760b90f 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> +++ b/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> @@ -74,6 +74,7 @@ cpu0: cpu@0 {
> enable-method = "psci";
> next-level-cache = <&l2>;
> clocks = <&scpi_dvfs 0>;
> + dynamic-power-coefficient = <140>;
> #cooling-cells = <2>;
> };
>
> @@ -84,6 +85,7 @@ cpu1: cpu@1 {
> enable-method = "psci";
> next-level-cache = <&l2>;
> clocks = <&scpi_dvfs 0>;
> + dynamic-power-coefficient = <140>;
> #cooling-cells = <2>;
> };
>
> @@ -94,6 +96,7 @@ cpu2: cpu@2 {
> enable-method = "psci";
> next-level-cache = <&l2>;
> clocks = <&scpi_dvfs 0>;
> + dynamic-power-coefficient = <140>;
> #cooling-cells = <2>;
> };
>
> @@ -104,6 +107,7 @@ cpu3: cpu@3 {
> enable-method = "psci";
> next-level-cache = <&l2>;
> clocks = <&scpi_dvfs 0>;
> + dynamic-power-coefficient = <140>;
> #cooling-cells = <2>;
> };
>
Reviewed-by: Neil Armstrong <[email protected]>