linux-kernel - Re: [PATCH v2 5/5] arm64: dts: ti: Add support for AM62-SK

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Message-ID: <20220224171031.n5hd456zmtezhhdb@debug>
Date:   Thu, 24 Feb 2022 11:10:31 -0600
From:   Nishanth Menon <nm@...com>
To:     Vignesh Raghavendra <vigneshr@...com>
CC:     Tero Kristo <kristo@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Marc Zyngier <maz@...nel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/5] arm64: dts: ti: Add support for AM62-SK

On 22:48-20220216, Vignesh Raghavendra wrote:
> From: Nishanth Menon <nm@...com>
> 
> AM62 StarterKit (SK) board is a low cost, small form factor board
> designed for TI’s AM625 SoC. It supports the following interfaces:
> * 2 GB DDR4 RAM

[...]
> +
> +	reserved-memory {
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
> +
> +		secure_tfa_ddr: tfa@...80000 {
> +			reg = <0x00 0x9e780000 0x00 0x80000>;
> +			alignment = <0x1000>;
> +			no-map;
> +		};
> +
> +		secure_ddr: optee@...00000 {
> +			reg = <0x00 0x9e800000 0x00 0x01800000>; /* for OP-TEE */
> +			alignment = <0x1000>;
> +			no-map;
> +		};
> +
> +		wkup_r5fss0_core0_dma_memory_region: r5f-dma-memory@...00000 {
> +			compatible = "shared-dma-pool";
> +			reg = <0x00 0xa0000000 0x00 0x200000>;
> +			no-map;
> +		};

Hate to bring this up so late in the review cycle.. but:

Could we update this so that we use 0xa0000000 (512MB as the outer
memory bound) and bring the firmware contiguous to that?

Else, we create a bit of holes in the memory map which will
create problems eventually as memory fragments.

While it is more optimal for this specific system to move the entire chunk
towards the far end of 2GB, I do realize that folks do use TI platforms
as the reference code and a reasonable usage of am62 (assuming gpu,
display, camera usage) is better done with 512MB.. Though smaller
systems may exist where further customizations is necessary..


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