linux-kernel - Re: [PATCH 2/3] arm64: dts: ti: k3-am62a7-sk: Reserve 576MiB of global CMA

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Date: Fri, 14 Jun 2024 12:27:01 -0500
From: Brandon Brnich <b-brnich@...com>
To: Devarsh Thakkar <devarsht@...com>
CC: <nm@...com>, <vigneshr@...com>, <kristo@...nel.org>, <robh@...nel.org>,
        <krzk+dt@...nel.org>, <conor+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <praneeth@...com>, <a-bhatia1@...com>,
        <j-luthra@...com>, <detheridge@...com>, <p-mantena@...com>,
        <vijayp@...com>
Subject: Re: [PATCH 2/3] arm64: dts: ti: k3-am62a7-sk: Reserve 576MiB of
 global CMA

Hi Devarsh,

On 20:39-20240613, Devarsh Thakkar wrote:
> Reserve 576MiB of CMA as global CMA pool starting after initial 1GiB of
> DDR.
> 
> AM62ax has different multimedia components such as Camera, Display, H.264
> VPU and JPEG Encoder which use CMA for buffer allocations.
> 
> The 12x 720x480 realtime VPU decode use-case requires 544MiB of CMA,
> additional 32MiB is kept as buffer in case some other peripheral also
> require it while VPU is running.
> 
> The reason to choose latter 1GiB is to not overlap with existing memory map
> which is utilizing initial 1GiB for remoteproc firmwares as shared here
> [1].
> 
> Also some drivers such as JPEG require 32bit addressing so not allocating
> from higher DDR address.
> 
> Link: https://lore.kernel.org/all/20240605124859.3034-5-hnagalla@ti.com [1]
> Signed-off-by: Devarsh Thakkar <devarsht@...com>

I have validated that this patch works with VPU. 

Tested-by: Brandon Brnich <b-brnich@...com>

Best,
Brandon

> ---
>  arch/arm64/boot/dts/ti/k3-am62a7-sk.dts | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts b/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
> index e026f65738b3..67faf46d7a35 100644
> --- a/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
> +++ b/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
> @@ -40,6 +40,15 @@ reserved-memory {
>  		#size-cells = <2>;
>  		ranges;
>  
> +		/* global cma region */
> +		linux,cma {
> +			compatible = "shared-dma-pool";
> +			reusable;
> +			size = <0x00 0x24000000>;
> +			alloc-ranges = <0x00 0xc0000000 0x00 0x24000000>;
> +			linux,cma-default;
> +		};
> +
>  		secure_tfa_ddr: tfa@...80000 {
>  			reg = <0x00 0x9e780000 0x00 0x80000>;
>  			alignment = <0x1000>;
> -- 
> 2.39.1
>