linux-kernel - Re: [PATCH] arm64: dts: meson: Add capacity-dmips-mhz attributes to G12B

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Date:   Thu, 19 Sep 2019 11:47:40 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Christian Hewitt <christianshewitt@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Kevin Hilman <khilman@...libre.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Frank Hartung <supervisedthinking@...il.com>
Subject: Re: [PATCH] arm64: dts: meson: Add capacity-dmips-mhz attributes to
 G12B

On 14/09/2019 04:49, Christian Hewitt wrote:
> From: Frank Hartung <supervisedthinking@...il.com>
> 
> From: Frank Hartung <supervisedthinking@...il.com>
> 
> Meson G12B SoCs (S922X and A311D) are a big-little design where not all CPUs
> are equal; the A53s cores are weaker than the A72s.
> 
> Include capacity-dmips-mhz properties to tell the OS there is a difference
> in processing capacity. The dmips values are based on similar submissions for
> other A53/A72 SoCs: HiSilicon 3660 [1] and Rockchip RK3399 [2].
> 
> This change is particularly beneficial for use-cases like retro gaming where
> emulators often run on a single core. The OS now chooses an A72 core instead
> of an A53 core.
> 
> [1] https://lore.kernel.org/patchwork/patch/862742/
> [2] https://patchwork.kernel.org/patch/10836577/
> 
> Signed-off-by: Frank Hartung <supervisedthinking@...il.com>
> Signed-off-by: Christian Hewitt <christianshewitt@...il.com>
> ---
>  arch/arm64/boot/dts/amlogic/meson-g12b.dtsi | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/amlogic/meson-g12b.dtsi b/arch/arm64/boot/dts/amlogic/meson-g12b.dtsi
> index 5628ccd..7f78d88 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-g12b.dtsi
> +++ b/arch/arm64/boot/dts/amlogic/meson-g12b.dtsi
> @@ -49,6 +49,7 @@
>  			compatible = "arm,cortex-a53";
>  			reg = <0x0 0x0>;
>  			enable-method = "psci";
> +			capacity-dmips-mhz = <592>;
>  			next-level-cache = <&l2>;
>  		};
>  
> @@ -57,6 +58,7 @@
>  			compatible = "arm,cortex-a53";
>  			reg = <0x0 0x1>;
>  			enable-method = "psci";
> +			capacity-dmips-mhz = <592>;
>  			next-level-cache = <&l2>;
>  		};
>  
> @@ -65,6 +67,7 @@
>  			compatible = "arm,cortex-a73";
>  			reg = <0x0 0x100>;
>  			enable-method = "psci";
> +			capacity-dmips-mhz = <1024>;
>  			next-level-cache = <&l2>;
>  		};
>  
> @@ -73,6 +76,7 @@
>  			compatible = "arm,cortex-a73";
>  			reg = <0x0 0x101>;
>  			enable-method = "psci";
> +			capacity-dmips-mhz = <1024>;
>  			next-level-cache = <&l2>;
>  		};
>  
> @@ -81,6 +85,7 @@
>  			compatible = "arm,cortex-a73";
>  			reg = <0x0 0x102>;
>  			enable-method = "psci";
> +			capacity-dmips-mhz = <1024>;
>  			next-level-cache = <&l2>;
>  		};
>  
> @@ -89,6 +94,7 @@
>  			compatible = "arm,cortex-a73";
>  			reg = <0x0 0x103>;
>  			enable-method = "psci";
> +			capacity-dmips-mhz = <1024>;
>  			next-level-cache = <&l2>;
>  		};
>  
> 

Reviewed-by: Neil Armstrong <narmstrong@...libre.com>