linux-kernel - Re: [PATCH 3/3] arm64: dts: ti: k3-am62p5-sk: Reserve 576 MiB of global CMA

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Message-ID: <20240614170409.zu4vaatdac4o6w2o@udba0500997>
Date: Fri, 14 Jun 2024 12:04:09 -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 3/3] arm64: dts: ti: k3-am62p5-sk: Reserve 576 MiB of
 global CMA

Hi Devarsh, 


On 20:39-20240613, Devarsh Thakkar wrote:
> From: Brandon Brnich <b-brnich@...com>
> 
> AM62p has different multimedia components such as Camera, Display, H264
> Video Codec which uses CMA for buffer allocations. We require 576MiB for 12
> channel decode-to-encode 720x480@...PS use case.
> 
> Signed-off-by: Brandon Brnich <b-brnich@...com>
> Signed-off-by: Devarsh Thakkar <devarsht@...com>
> ---
>  arch/arm64/boot/dts/ti/k3-am62p5-sk.dts | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-am62p5-sk.dts b/arch/arm64/boot/dts/ti/k3-am62p5-sk.dts
> index fb980d46e304..5ef74d9f8eea 100644
> --- a/arch/arm64/boot/dts/ti/k3-am62p5-sk.dts
> +++ b/arch/arm64/boot/dts/ti/k3-am62p5-sk.dts
> @@ -48,6 +48,13 @@ reserved-memory {
>  		#size-cells = <2>;
>  		ranges;
>  
> +		linux,cma {
> +			compatible = "shared-dma-pool";
> +			reusable;
> +			size = <0x00 0x24000000>;
> +			linux,cma-default;
> +		};

Since AM62p has 8gb memory, this allocation can come from upper portion.
Doing so breaks Wave5 encoding/decoding as the driver can not yet handle
48 bit addressing. 48bit support is scheduled to be upstreamed, but unsure of
when this will actually make it in.  

Could we force this into lower 32bits using same
alloc-ranges as done in your AM62a patch[0]?


[0]: https://patchwork.kernel.org/project/linux-arm-kernel/patch/20240613150902.2173582-3-devarsht@ti.com/

Best,
Brandon

> +
>  		secure_tfa_ddr: tfa@...80000 {
>  			reg = <0x00 0x9e780000 0x00 0x80000>;
>  			no-map;
> -- 
> 2.39.1
>