linux-kernel - Re: [PATCH v2 47/48] ARM: tegra: ventana: Support CPU voltage scaling and thermal throttling

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Date:   Thu, 17 Dec 2020 19:28:23 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 47/48] ARM: tegra: ventana: Support CPU voltage scaling
 and thermal throttling

On 17/12/2020 19:06, Dmitry Osipenko wrote:
> Enable CPU voltage scaling and thermal throttling on Tegra20 Ventana board.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  arch/arm/boot/dts/tegra20-ventana.dts | 40 ++++++++++++++++++++++++++-
>  1 file changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/boot/dts/tegra20-ventana.dts b/arch/arm/boot/dts/tegra20-ventana.dts
> index 14ace2ef749c..c2d9f38960bc 100644
> --- a/arch/arm/boot/dts/tegra20-ventana.dts
> +++ b/arch/arm/boot/dts/tegra20-ventana.dts
> @@ -2,8 +2,10 @@
>  /dts-v1/;
>  
>  #include <dt-bindings/input/input.h>
> +#include <dt-bindings/thermal/thermal.h>
>  #include "tegra20.dtsi"
>  #include "tegra20-cpu-opp.dtsi"
> +#include "tegra20-cpu-opp-microvolt.dtsi"
>  
>  / {
>  	model = "NVIDIA Tegra20 Ventana evaluation board";
> @@ -527,9 +529,10 @@ ldo_rtc {
>  			};
>  		};
>  
> -		temperature-sensor@4c {
> +		nct1008: temperature-sensor@4c {
>  			compatible = "onnn,nct1008";
>  			reg = <0x4c>;
> +			#thermal-sensor-cells = <1>;
>  		};
>  	};
>  
> @@ -615,10 +618,13 @@ clk32k_in: clock@0 {
>  
>  	cpus {
>  		cpu0: cpu@0 {
> +			cpu-supply = <&vdd_cpu>;
>  			operating-points-v2 = <&cpu0_opp_table>;
> +			#cooling-cells = <2>;
>  		};
>  
>  		cpu@1 {
> +			cpu-supply = <&vdd_cpu>;
>  			operating-points-v2 = <&cpu0_opp_table>;
>  		};
>  	};
> @@ -717,4 +723,36 @@ sound {
>  			 <&tegra_car TEGRA20_CLK_CDEV1>;
>  		clock-names = "pll_a", "pll_a_out0", "mclk";
>  	};
> +
> +	thermal-zones {
> +		cpu-thermal {
> +			polling-delay-passive = <1000>; /* milliseconds */
> +			polling-delay = <5000>; /* milliseconds */
> +
> +			thermal-sensors = <&nct1008 1>;
> +
> +			trips {
> +				trip0: cpu-alert0 {
> +					/* start throttling at 50C */
> +					temperature = <50000>;
> +					hysteresis = <200>;

Did you mean <2000> ?

> +					type = "passive";
> +				};
> +
> +				trip1: cpu-crit {
> +					/* shut down at 60C */
> +					temperature = <60000>;
> +					hysteresis = <2000>;

I think you can drop the hysteresis here, when the critical temperature
is reached, there is an emergency shutdown.

50°C and 60°C sound very low values, no ?

> +					type = "critical";
> +				};
> +			};
> +
> +			cooling-maps {
> +				map0 {
> +					trip = <&trip0>;
> +					cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;

You should add all CPUs here.

> +				};
> +			};
> +		};
> +	};
>  };
> 


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