linux-kernel - [PATCH] riscv: dts: sophgo: fix DMA data-width configuration for CV18xx

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Message-Id: <20250428-duo-dma-config-v1-1-eb6ad836ca42@whut.edu.cn>
Date: Mon, 28 Apr 2025 17:24:36 +0800
From: Ze Huang <huangze@...t.edu.cn>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Chen Wang <unicorn_wang@...look.com>, 
 Inochi Amaoto <inochiama@...il.com>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Alexandre Ghiti <alex@...ti.fr>
Cc: devicetree@...r.kernel.org, sophgo@...ts.linux.dev, 
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Yu Yuan <yu.yuan@...u.edu.cn>, Ze Huang <huange@...t.edu.cn>, 
 Ze Huang <huangze@...t.edu.cn>
Subject: [PATCH] riscv: dts: sophgo: fix DMA data-width configuration for
 CV18xx

The "snps,data-width" property[1] defines the AXI data width of the DMA
controller as:

    width = 8 × (2^n) bits

(0 = 8 bits, 1 = 16 bits, 2 = 32 bits, ..., 6 = 512 bits)
where "n" is the value of "snps,data-width".

For the CV18xx DMA controller, the correct AXI data width is 32 bits,
corresponding to "snps,data-width = 2".

Test results on Milkv Duo S can be found here [2].

Link: https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/dma/snps%2Cdw-axi-dmac.yaml#L74 [1]
Link: https://gist.github.com/Sutter099/4fa99bb2d89e5af975983124704b3861 [2]

Co-developed-by: Yu Yuan <yu.yuan@...u.edu.cn>
Signed-off-by: Yu Yuan <yu.yuan@...u.edu.cn>
Signed-off-by: Ze Huang <huange@...t.edu.cn>
---
Signed-off-by: Ze Huang <huangze@...t.edu.cn>
---
 arch/riscv/boot/dts/sophgo/cv18xx.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/boot/dts/sophgo/cv18xx.dtsi b/arch/riscv/boot/dts/sophgo/cv18xx.dtsi
index c18822ec849f353bc296965d2d600a3df314cff6..58cd546392e056a3bbdf9c27a73c050de1060fba 100644
--- a/arch/riscv/boot/dts/sophgo/cv18xx.dtsi
+++ b/arch/riscv/boot/dts/sophgo/cv18xx.dtsi
@@ -341,7 +341,7 @@ dmac: dma-controller@...0000 {
 					   1024 1024 1024 1024>;
 			snps,priority = <0 1 2 3 4 5 6 7>;
 			snps,dma-masters = <2>;
-			snps,data-width = <4>;
+			snps,data-width = <2>;
 			status = "disabled";
 		};
 

---
base-commit: b4432656b36e5cc1d50a1f2dc15357543add530e
change-id: 20250428-duo-dma-config-feb4e5e0546f

Best regards,
-- 
Ze Huang <huangze@...t.edu.cn>