linux-kernel - Re: [PATCHv1 2/5] arm64: dts: amlogic: Add cache information to the Amlogic SM1 SoC

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Message-ID: <26732d5a-9fe1-4662-9362-ed397d266e01@linaro.org>
Date: Tue, 6 Feb 2024 09:54:23 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Anand Moon <linux.amoon@...il.com>, Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>, Kevin Hilman <khilman@...libre.com>,
 Jerome Brunet <jbrunet@...libre.com>,
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc: devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv1 2/5] arm64: dts: amlogic: Add cache information to the
 Amlogic SM1 SoC

On 05/02/2024 18:19, Anand Moon wrote:
> As per S905X3 datasheet add missing cache information to the Amlogic
> SM1 SoC. ARM Cortex-A55 CPU uses unified L3 cache instead of L2 cache.
> 
> - Each Cortex-A55 core has 32KB of L1 instruction cache available and
> 	32KB of L1 data cache available.
> - Along with 512KB Unified L3 cache.

This 512K number is for the NPU, AFAIK the CPU L3 Cache size isn't specified in the datasheet

> 
> To improve system performance.
> 
> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> ---
> Datasheet
> [0] https://dn.odroid.com/S905X3/ODROID-C4/Docs/S905X3_Public_Datasheet_Hardkernel.pdf
> [1] https://en.wikipedia.org/wiki/ARM_Cortex-A55
> ---
>   arch/arm64/boot/dts/amlogic/meson-sm1.dtsi | 39 ++++++++++++++++++----
>   1 file changed, 33 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/amlogic/meson-sm1.dtsi b/arch/arm64/boot/dts/amlogic/meson-sm1.dtsi
> index 643f94d9d08e..403443e782e4 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-sm1.dtsi
> +++ b/arch/arm64/boot/dts/amlogic/meson-sm1.dtsi
> @@ -55,7 +55,13 @@ cpu0: cpu@0 {
>   			compatible = "arm,cortex-a55";
>   			reg = <0x0 0x0>;
>   			enable-method = "psci";
> -			next-level-cache = <&l2>;
> +			d-cache-line-size = <32>;
> +			d-cache-size = <0x8000>;
> +			d-cache-sets = <32>;
> +			i-cache-line-size = <32>;
> +			i-cache-size = <0x8000>;
> +			i-cache-sets = <32>;
> +			next-level-cache = <&l3>;
>   			#cooling-cells = <2>;
>   		};
>   
> @@ -64,7 +70,13 @@ cpu1: cpu@1 {
>   			compatible = "arm,cortex-a55";
>   			reg = <0x0 0x1>;
>   			enable-method = "psci";
> -			next-level-cache = <&l2>;
> +			d-cache-line-size = <32>;
> +			d-cache-size = <0x8000>;
> +			d-cache-sets = <32>;
> +			i-cache-line-size = <32>;
> +			i-cache-size = <0x8000>;
> +			i-cache-sets = <32>;
> +			next-level-cache = <&l3>;
>   			#cooling-cells = <2>;
>   		};
>   
> @@ -73,7 +85,13 @@ cpu2: cpu@2 {
>   			compatible = "arm,cortex-a55";
>   			reg = <0x0 0x2>;
>   			enable-method = "psci";
> -			next-level-cache = <&l2>;
> +			d-cache-line-size = <32>;
> +			d-cache-size = <0x8000>;
> +			d-cache-sets = <32>;
> +			i-cache-line-size = <32>;
> +			i-cache-size = <0x8000>;
> +			i-cache-sets = <32>;
> +			next-level-cache = <&l3>;
>   			#cooling-cells = <2>;
>   		};
>   
> @@ -82,14 +100,23 @@ cpu3: cpu@3 {
>   			compatible = "arm,cortex-a55";
>   			reg = <0x0 0x3>;
>   			enable-method = "psci";
> -			next-level-cache = <&l2>;
> +			d-cache-line-size = <32>;
> +			d-cache-size = <0x8000>;
> +			d-cache-sets = <32>;
> +			i-cache-line-size = <32>;
> +			i-cache-size = <0x8000>;
> +			i-cache-sets = <32>;
> +			next-level-cache = <&l3>;
>   			#cooling-cells = <2>;
>   		};
>   
> -		l2: l2-cache0 {
> +		l3: l3-cache0 {
>   			compatible = "cache";
> -			cache-level = <2>;
> +			cache-level = <3>;
>   			cache-unified;
> +			cache-size = <0x7d000>; /* L2. 512 KB */

Comment should be L3 here

> +			cache-line-size = <64>;
> +			cache-sets = <512>;
>   		};
>   	};
>   

Thanks,
Neil