linux-kernel - Re: [PATCH 2/2] rockchip: dts: Enable UART DMA by adding default dma-names property

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Message-ID: <3477683.usfYGdeWWP@diego>
Date: Thu, 18 Sep 2025 18:22:12 +0200
From: Heiko Stübner <heiko@...ech.de>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Ed Wildgoose <lists@...dgooses.com>,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Ed Wildgoose <lists@...dgooses.com>
Subject:
 Re: [PATCH 2/2] rockchip: dts: Enable UART DMA by adding default dma-names
 property

Hi,

Am Donnerstag, 18. September 2025, 11:32:46 Mitteleuropäische Sommerzeit schrieb Ed Wildgoose:
> Kernel appears to need a dma-names set for DMA to actually enable. Set a
> default dma-names property for all UARTs defined in the board
> definition: rk3566-radxa-zero-3.dtsi
> 
> This is tested on a Radxa Zero 3W (which has 5x UARTs) and removes the
> warnings and enables DMA on this platform

the kernel does not _need_ the dmas and the uart will work just fine
without.

And as was pointed out in the previous version, the uarts have possible
stability issues, when connected to specific peripherals

So I'd prefer to not enable uart dmas "just for fun".

Heiko


> Signed-off-by: Ed Wildgoose <lists@...dgooses.com>
> ---
>  arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi b/arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi
> index e644bfc9c..fc26a4a52 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi
> @@ -488,21 +488,29 @@ &tsadc {
>  	status = "okay";
>  };
>  
> +&uart1 {
> +	dma-names = "tx", "rx";
> +};
> +
>  &uart2 {
> +	dma-names = "tx", "rx";
>  	status = "okay";
>  };
>  
>  &uart4{
> +	dma-names = "tx", "rx";
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&uart4m1_xfer>;
>  };
>  
>  &uart5 {
> +	dma-names = "tx", "rx";
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&uart5m1_xfer>;
>  };
>  
>  &uart9 {
> +	dma-names = "tx", "rx";
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&uart9m1_xfer>;
>  };
>