linux-kernel - Re: [PATCH 3/3] arm64: dts: rockchip: set rk3399 dynamic CPU power coefficients

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Date:   Fri, 23 Jun 2017 20:39:25 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Brian Norris <briannorris@...omium.org>
Cc:     linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Caesar Wang <wxt@...k-chips.com>,
        Doug Anderson <dianders@...omium.org>,
        linux-arm-kernel@...ts.infradead.org,
        Matthias Kaehlcke <mka@...omium.org>
Subject: Re: [PATCH 3/3] arm64: dts: rockchip: set rk3399 dynamic CPU power coefficients

Am Freitag, 23. Juni 2017, 10:07:37 CEST schrieb Brian Norris:
> Provide the dynamic power coefficient of the big and little CPU
> clusters. These numbers are currently in use on the Samsung Chromebook
> Plus ("Kevin").
> 
> The power allocator thermal governor doesn't know how to do anything if
> it doesn't get power parameters from its cooling devices (in this case,
> CPUfreq). So this effectively enables the power-allocator governor.
> 
> Signed-off-by: Brian Norris <briannorris@...omium.org>
> ---
>  arch/arm64/boot/dts/rockchip/rk3399.dtsi | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> index 69c56f7316c4..4f6667547814 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> @@ -109,6 +109,7 @@
>  			reg = <0x0 0x0>;
>  			enable-method = "psci";
>  			#cooling-cells = <2>; /* min followed by max */
> +			dynamic-power-coefficient = <100>;
>  			clocks = <&cru ARMCLKL>;
>  		};
>  
> @@ -142,6 +143,7 @@
>  			reg = <0x0 0x100>;
>  			enable-method = "psci";
>  			#cooling-cells = <2>; /* min followed by max */
> +			dynamic-power-coefficient = <100>;
>  			clocks = <&cru ARMCLKB>;
>  		};
>  
> 

I think these should be set for all cores, similar to clocks. While
cpufreq and friends regularly only take the first number, in a
hw-description sense, it should be part of every core in the dt.


Heiko