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Date:   Wed, 12 Apr 2023 14:56:56 -0500
From:   Nishanth Menon <nm@ti.com>
To:     Udit Kumar <u-kumar1@ti.com>
CC:     <linux-arm-kernel@lists.infradead.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <vigneshr@ti.com>, <kristo@kernel.org>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <a-govindraju@ti.com>,
        <kishon@ti.com>, <n-dasan@ti.com>
Subject: Re: [PATCH] arm64: dts: ti: k3-j721s2-main: fix msmc node
Message-ID: <20230412195656.a53nalvjuhelniz4@populace>
References: <20230412173609.1307837-1-u-kumar1@ti.com>
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On 23:06-20230412, Udit Kumar wrote:
> On J721S2 SOC, l3cache-sram size is configured as zero by
> system firmware.
> Also top 64K of msmc_ram (0x703F_0000 to 0x703F_FFFF) is used by system
> firmware tifs-sram.
> 
> This patch removes l3cache-sram node and update range for tifs-sram.
> 
> Fixes: b8545f9d3a54 ("arm64: dts: ti: Add initial support for J721S2 SoC")
> 
> Signed-off-by: Udit Kumar <u-kumar1@ti.com>
> ---
>  arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
> index 2dd7865f7654..cbc784f915a9 100644
> --- a/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
> @@ -17,13 +17,10 @@ atf-sram@0 {
>  			reg = <0x0 0x20000>;
>  		};
>  
> -		tifs-sram@1f0000 {
> -			reg = <0x1f0000 0x10000>;
> +		tifs-sram@3f0000 {
> +			reg = <0x3f0000 0x10000>;
>  		};
>  
> -		l3cache-sram@200000 {
> -			reg = <0x200000 0x200000>;
> -		};
>  	};
>  
>  	gic500: interrupt-controller@1800000 {
> -- 
> 2.34.1
> 

Are you saying that j721s2 is incapable of l3 cache? say some level 1
errata?

or is it because, the chip is really capable of l3 cache and we are
really setting it to 0?

https://git.ti.com/cgit/k3-image-gen/k3-image-gen/tree/soc/j721s2/evm/board-cfg.c#n71

unless the chip has an errata, you are supposed to fix it up based on
configuration by using the API and this patch is a NAK
https://software-dl.ti.com/tisci/esd/latest/2_tisci_msgs/general/core.html#tisci-query-msmc

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D