On 24/02/2020 17:54, Ondrej Jirman wrote:
> This enables passive cooling by down-regulating CPU voltage
> and frequency.
> 
> For the trip points, I used values from the BSP code directly.
> 
> The critical trip point value is 30°C above the maximum recommended
> ambient temperature (70°C) for the SoC from the datasheet, so there's
> some headroom even at such a high ambient temperature.
> 
> Signed-off-by: Ondrej Jirman <[email protected]>
> ---
>  arch/arm/boot/dts/sun8i-a83t.dtsi | 60 +++++++++++++++++++++++++++----
>  1 file changed, 54 insertions(+), 6 deletions(-)
> 
> v2:
> - added more detail to the commit description
> 
> diff --git a/arch/arm/boot/dts/sun8i-a83t.dtsi 
> b/arch/arm/boot/dts/sun8i-a83t.dtsi
> index 74ac7ee9383cf..53c2b6a836f27 100644
> --- a/arch/arm/boot/dts/sun8i-a83t.dtsi
> +++ b/arch/arm/boot/dts/sun8i-a83t.dtsi
> @@ -72,7 +72,7 @@ cpu0: cpu@0 {
>                       #cooling-cells = <2>;
>               };
>  
> -             cpu@1 {
> +             cpu1: cpu@1 {
>                       compatible = "arm,cortex-a7";
>                       device_type = "cpu";
>                       clocks = <&ccu CLK_C0CPUX>;
> @@ -83,7 +83,7 @@ cpu@1 {
>                       #cooling-cells = <2>;
>               };
>  
> -             cpu@2 {
> +             cpu2: cpu@2 {
>                       compatible = "arm,cortex-a7";
>                       device_type = "cpu";
>                       clocks = <&ccu CLK_C0CPUX>;
> @@ -94,7 +94,7 @@ cpu@2 {
>                       #cooling-cells = <2>;
>               };
>  
> -             cpu@3 {
> +             cpu3: cpu@3 {
>                       compatible = "arm,cortex-a7";
>                       device_type = "cpu";
>                       clocks = <&ccu CLK_C0CPUX>;
> @@ -116,7 +116,7 @@ cpu100: cpu@100 {
>                       #cooling-cells = <2>;
>               };
>  
> -             cpu@101 {
> +             cpu101: cpu@101 {
>                       compatible = "arm,cortex-a7";
>                       device_type = "cpu";
>                       clocks = <&ccu CLK_C1CPUX>;
> @@ -127,7 +127,7 @@ cpu@101 {
>                       #cooling-cells = <2>;
>               };
>  
> -             cpu@102 {
> +             cpu102: cpu@102 {
>                       compatible = "arm,cortex-a7";
>                       device_type = "cpu";
>                       clocks = <&ccu CLK_C1CPUX>;
> @@ -138,7 +138,7 @@ cpu@102 {
>                       #cooling-cells = <2>;
>               };
>  
> -             cpu@103 {
> +             cpu103: cpu@103 {
>                       compatible = "arm,cortex-a7";
>                       device_type = "cpu";
>                       clocks = <&ccu CLK_C1CPUX>;
> @@ -1188,12 +1188,60 @@ cpu0_thermal: cpu0-thermal {
>                       polling-delay-passive = <0>;
>                       polling-delay = <0>;
>                       thermal-sensors = <&ths 0>;
> +
> +                     trips {
> +                             cpu0_hot: cpu-hot {
> +                                     temperature = <80000>;
> +                                     hysteresis = <2000>;
> +                                     type = "passive";
> +                             };
> +
> +                             cpu0_very_hot: cpu-very-hot {
> +                                     temperature = <100000>;
> +                                     hysteresis = <0>;
> +                                     type = "critical";
> +                             };
> +                     };
> +
> +                     cooling-maps {
> +                             cpu-hot-limit {
> +                                     trip = <&cpu0_hot>;
> +                                     cooling-device = <&cpu0 
> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> +                                                      <&cpu1 
> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> +                                                      <&cpu2 
> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> +                                                      <&cpu3 
> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
> +                             };
> +                     };
>               };
>  
>               cpu1_thermal: cpu1-thermal {
>                       polling-delay-passive = <0>;

No polling to mitigate?

>                       polling-delay = <0>;
>                       thermal-sensors = <&ths 1>;
> +
> +                     trips {
> +                             cpu1_hot: cpu-hot {
> +                                     temperature = <80000>;
> +                                     hysteresis = <2000>;
> +                                     type = "passive";

I'm curious, can you really reach this temperature with a cortex-a7
running at 1.2GHz max?

> +                             };
> +
> +                             cpu1_very_hot: cpu-very-hot {
> +                                     temperature = <100000>;
> +                                     hysteresis = <0>;
> +                                     type = "critical";
> +                             };
> +                     };
> +
> +                     cooling-maps {
> +                             cpu-hot-limit {
> +                                     trip = <&cpu1_hot>;
> +                                     cooling-device = <&cpu100 
> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> +                                                      <&cpu101 
> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> +                                                      <&cpu102 
> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> +                                                      <&cpu103 
> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
> +                             };
> +                     };
>               };
>  
>               gpu_thermal: gpu-thermal {
> 


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