linux-kernel - Re: [PATCH] arm64: dts: rockchip: update dynamic-power-coefficient for rk3399

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Message-ID: <1954724.bYQfYcfQLC@phil>
Date:   Tue, 01 Aug 2017 01:02:04 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Caesar Wang <wxt@...k-chips.com>
Cc:     linux-rockchip@...ts.infradead.org,
        Douglas Anderson <dianders@...omium.org>,
        William wu <wulf@...k-chips.com>,
        Elaine Zhang <zhangqing@...k-chips.com>,
        Kever Yang <kever.yang@...k-chips.com>,
        Brian Norris <briannorris@...omium.org>,
        linux-kernel@...r.kernel.org, Shawn Lin <shawn.lin@...k-chips.com>,
        devicetree@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Roger Chen <roger.chen@...k-chips.com>
Subject: Re: [PATCH] arm64: dts: rockchip: update dynamic-power-coefficient for rk3399

Am Dienstag, 25. Juli 2017, 17:22:55 CEST schrieb Caesar Wang:
> This patch updates the dynamic-power-coefficient for big cluster on
> rk3399 SoCs.
> 
> The dynamic power consumption of the CPU is proportional to the square of
> the Voltage (V) and the clock frequency (f). The coefficient is used to
> calculate the dynamic power as below -
> Pdyn = dynamic-power-coefficient * V^2 * f
> Where Voltage is in uV, frequency is in MHz.
> 
> As the following is the tested data on rk3399's big cluster.
> frequency(MHz)  Voltage(V)  Current(mA) Dynamic-power-coefficient
> 24              0.8         15
> 48              0.8         23          ~417
> 96              0.8         40          ~443
> 216             0.8         82          ~438
> 312             0.8         115         ~430
> 408             0.8         150         ~455
> So the dynamic-power-coefficient average value is about 436.
> 
> Signed-off-by: Caesar Wang <wxt@...k-chips.com>

applied for 4.14 and thanks for that very nice and informative commit
message explaining the testing methodology.


Heiko

> ---
> 
>  arch/arm64/boot/dts/rockchip/rk3399.dtsi | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> index 9d02006..5d54a06 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> @@ -150,7 +150,7 @@
>  			enable-method = "psci";
>  			#cooling-cells = <2>; /* min followed by max */
>  			clocks = <&cru ARMCLKB>;
> -			dynamic-power-coefficient = <100>;
> +			dynamic-power-coefficient = <436>;
>  		};
>  
>  		cpu_b1: cpu@101 {
> @@ -159,7 +159,7 @@
>  			reg = <0x0 0x101>;
>  			enable-method = "psci";
>  			clocks = <&cru ARMCLKB>;
> -			dynamic-power-coefficient = <100>;
> +			dynamic-power-coefficient = <436>;
>  		};
>  	};
>  
>