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

From: Dragan Simic <dsimic@manjaro.org>
To: Ed Wildgoose <lists@wildgooses.com>
Cc: Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Heiko Stuebner <heiko@sntech.de>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] rockchip: dts: Enable UART DMA by adding default dma-names property
Date: Wed, 17 Sep 2025 14:22:52 +0200	[thread overview]
Message-ID: <7c8576e3d9fc73ba45830833f5281706@manjaro.org> (raw)
In-Reply-To: <20250917114932.25994-3-lists@wildgooses.com>

Hello Ed,

On 2025-09-17 13:49, Ed Wildgoose wrote:
> 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 base 
> rk356x-base
> dtsi
> 
> This is tested on a Radxa Zero 3W (which has 5x UARTs) and removes the
> warnings and enables DMA on this platform

Thanks for the patches.

We should (still) stay away from defining the "dma-names" property
at the SoC level, because doing that causes serious issues in certain
cases.  Thus, I'd suggest that this patch is dropped, and that the
"dma-names" property is defined instead at the board level, where
it's needed and tested to work as expected.

Please see commit bf6f26deb0e8 (arm64: dts: rockchip: Add dma-names
to uart1 on quartz64-b, 2024-06-28) for further explanation.

If/when the underlying issues are debugged and resolved, we can get
back to defining the "dma-names" property at the SoC level.