Re: [PATCH] arm64: dts: renesas: r8a779g3: Update thermal trip points on V4H Sparrow Hawk

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hi Marek,

Thanks for your work.

On 2025-06-25 12:01:56 +0200, Marek Vasut wrote:
> Since the Sparrow Hawk has a smaller PCB than the White Hawk, it tends
> to generate more heat. To prevent potential damage to the board, adjust
> the temperature trip points.
> 
> Add four "passive" trip points which increasingly throttle the CPU to
> prevent overheating. The first trip point at 68°C disables the 1.8 GHz
> and 1.7 GHz modes and limits the CPU to 1.5 GHz frequency. The second
> trip point at 72°C disables the 1.5 GHz mode and limits the CPU to 1.0
> GHz frequency. The third trip point at 76°C uses thermal-idle to start
> inserting idle cycles into the CPU instruction stream to cool the CPU
> cores down. The fourth and last trip point at 80°C disables the 1.0 GHz
> mode and limits the CPU to 500 MHz frequency.
> 
> In case the SoC heats up further, in case either of the thermal sensors
> readings passes the 100°C, a thermal shutdown is triggered to prevent
> any damage to the hardware.
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
> ---
> Cc: Conor Dooley <conor+dt@kernel.org>
> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
> Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
> Cc: Magnus Damm <magnus.damm@gmail.com>
> Cc: "Niklas Söderlund" <niklas.soderlund@ragnatech.se>
> Cc: Rob Herring <robh@kernel.org>
> Cc: devicetree@vger.kernel.org
> Cc: linux-renesas-soc@vger.kernel.org
> ---
>  .../dts/renesas/r8a779g3-sparrow-hawk.dts     | 137 ++++++++++++++++++
>  1 file changed, 137 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk.dts b/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk.dts
> index 9ba23129e65e..ba81df3c779d 100644
> --- a/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk.dts
> +++ b/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk.dts
> @@ -38,6 +38,7 @@
>  
>  /dts-v1/;
>  #include <dt-bindings/gpio/gpio.h>
> +#include <dt-bindings/thermal/thermal.h>
>  
>  #include "r8a779g3.dtsi"
>  
> @@ -797,3 +798,139 @@ &rwdt {
>  &scif_clk {	/* X12 */
>  	clock-frequency = <24000000>;
>  };
> +
> +/* thermal-idle cooling for all SoC cores */
> +&a76_0 {
> +	#cooling-cells = <2>;
> +
> +	a76_0_thermal_idle: thermal-idle {
> +		#cooling-cells = <2>;
> +		duration-us = <10000>;
> +		exit-latency-us = <500>;
> +	};
> +};
> +
> +&a76_1 {
> +	a76_1_thermal_idle: thermal-idle {
> +		#cooling-cells = <2>;
> +		duration-us = <10000>;
> +		exit-latency-us = <500>;
> +	};
> +};
> +
> +&a76_2 {
> +	a76_2_thermal_idle: thermal-idle {
> +		#cooling-cells = <2>;
> +		duration-us = <10000>;
> +		exit-latency-us = <500>;
> +	};
> +};
> +
> +&a76_3 {
> +	a76_3_thermal_idle: thermal-idle {
> +		#cooling-cells = <2>;
> +		duration-us = <10000>;
> +		exit-latency-us = <500>;
> +	};
> +};

I did not know you could do this and use it as a cooling device, thanks 
for teaching me something new!

> +
> +/* THS sensors in SoC, critical temperature trip point is 100C */
> +&sensor1_crit {
> +	temperature = <100000>;
> +};
> +
> +&sensor2_crit {
> +	temperature = <100000>;
> +};
> +
> +&sensor3_crit {
> +	temperature = <100000>;
> +};
> +
> +&sensor4_crit {
> +	temperature = <100000>;
> +};
> +
> +&sensor_thermal_cr52 {
> +	critical-action = "shutdown";
> +};
> +
> +&sensor_thermal_cnn {
> +	critical-action = "shutdown";
> +};

Is this not the default action for critical trip points? In my testing 
in the past R-Car systems have always shutdown when the critical trip is 
reached. If it's not I think we should move these to r8a779g0.dtsi. And 
likely add them for all other SoCs too?

> +
> +/* THS sensor in SoC near CA76 cores does more progressive cooling. */
> +&sensor_thermal_ca76 {
> +	critical-action = "shutdown";
> +
> +	cooling-maps {
> +		/*
> +		 * The cooling-device minimum and maximum parameters inversely
> +		 * match opp-table-0 {} node entries in r8a779g0.dtsi, in other
> +		 * words, 0 refers to 1.8 GHz OPP and 4 refers to 500 MHz OPP.
> +		 * This is because they refer to cooling levels, where maximum
> +		 * cooling level happens at 500 MHz OPP, when the CPU core is
> +		 * running slowly and therefore generates least heat.
> +		 */
> +		map0 {
> +			/* At 68C, inhibit 1.7 GHz and 1.8 GHz modes */
> +			trip = <&sensor3_passive_low>;
> +			cooling-device = <&a76_0 2 4>;
> +			contribution = <128>;
> +		};
> +
> +		map1 {
> +			/* At 72C, inhibit 1.5 GHz mode */
> +			trip = <&sensor3_passive_mid>;
> +			cooling-device = <&a76_0 3 4>;
> +			contribution = <256>;
> +		};
> +
> +		map2 {
> +			/* At 76C, start injecting idle states */
> +			trip = <&sensor3_passive_hi>;
> +			cooling-device = <&a76_0_thermal_idle 0 80>,
> +					 <&a76_1_thermal_idle 0 80>,
> +					 <&a76_2_thermal_idle 0 80>,
> +					 <&a76_3_thermal_idle 0 80>;
> +			contribution = <512>;
> +		};
> +
> +		map3 {
> +			/* At 80C, inhibit 1.0 GHz mode */
> +			trip = <&sensor3_passive_crit>;
> +			cooling-device = <&a76_0 4 4>;
> +			contribution = <1024>;
> +		};
> +	};
> +
> +	trips {
> +		sensor3_passive_low: sensor3-passive-low {
> +			temperature = <68000>;
> +			hysteresis = <2000>;
> +			type = "passive";
> +		};
> +
> +		sensor3_passive_mid: sensor3-passive-mid {
> +			temperature = <72000>;
> +			hysteresis = <2000>;
> +			type = "passive";
> +		};
> +
> +		sensor3_passive_hi: sensor3-passive-hi {
> +			temperature = <76000>;
> +			hysteresis = <2000>;
> +			type = "passive";
> +		};
> +
> +		sensor3_passive_crit: sensor3-passive-crit {
> +			temperature = <80000>;
> +			hysteresis = <2000>;
> +			type = "passive";
> +		};
> +	};
> +};
> +
> +&sensor_thermal_ddr1 {
> +	critical-action = "shutdown";
> +};
> -- 
> 2.47.2
> 

-- 
Kind Regards,
Niklas Söderlund