linux-kernel - Re: [PATCH 5/8] riscv: dts: spacemit: Add dma bus and PDMA node for K1 SoC

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Message-ID: <2b17769e-2620-4f22-9ea5-f15d4adcb27b@dram.page>
Date: Fri, 13 Jun 2025 11:06:43 +0800
From: Vivian Wang <uwu@...m.page>
To: Guodong Xu <guodong@...cstar.com>, vkoul@...nel.org, robh@...nel.org,
 krzk+dt@...nel.org, conor+dt@...nel.org, dlan@...too.org,
 paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
 alex@...ti.fr, p.zabel@...gutronix.de, drew@...7.com,
 emil.renner.berthing@...onical.com, inochiama@...il.com,
 geert+renesas@...der.be, tglx@...utronix.de, hal.feng@...rfivetech.com,
 joel@....id.au, duje.mihanovic@...le.hr, Ze Huang <huangze@...t.edu.cn>
Cc: elder@...cstar.com, dmaengine@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev
Subject: Re: [PATCH 5/8] riscv: dts: spacemit: Add dma bus and PDMA node for
 K1 SoC

Hi Guodong,

On 6/11/25 20:57, Guodong Xu wrote:
> <snip>
>
> -			status = "disabled";
> +		dma_bus: bus@4 {
> +			compatible = "simple-bus";
> +			#address-cells = <2>;
> +			#size-cells = <2>;
> +			dma-ranges = <0x0 0x00000000 0x0 0x00000000 0x0 0x80000000>,
> +				     <0x1 0x00000000 0x1 0x80000000 0x3 0x00000000>;
> +			ranges;
>  		};

Can the addition of dma_bus and movement of nodes under it be extracted
into a separate patch, and ideally, taken up by Yixun Lan without going
through dmaengine? Not specifically "dram_range4", but all of these
translations affects many devices on the SoC, including ethernet and
USB3. See:

https://lore.kernel.org/all/20250526-b4-k1-dwc3-v3-v4-2-63e4e525e5cb@whut.edu.cn/
https://lore.kernel.org/all/20250613-net-k1-emac-v1-0-cc6f9e510667@iscas.ac.cn/

(I haven't put eth{0,1} under dma_bus5 because in 6.16-rc1 there is
none, but ideally we should fix this.)

DMA address translation does not depend on PDMA. It would be best if we
get all the possible dma-ranges buses handled in one place, instead of
everyone moving nodes around.

@Ze Huang: This affects your "MBUS" changes as well. Please take a look,
thanks.

>  
>  		gpio: gpio@...19000 {
> @@ -792,3 +693,124 @@ pwm19: pwm@...22c00 {
>  		};
>  	};
>  };
> +
> +&dma_bus {
>
> <snip>