linux-kernel - Re: [PATCH] arm64: dts: rockchip: Add dma-names to uart1 on quartz64-b

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Date: Sat, 29 Jun 2024 07:05:41 +0200
From: Dragan Simic <dsimic@...jaro.org>
To: Diederik de Haas <didi.debian@...ow.org>
Cc: Heiko Stuebner <heiko@...ech.de>, Jonas Karlman <jonas@...boo.se>,
 Uwe Kleine-König <ukleinek@...ian.org>, Chen-Yu Tsai
 <wens@...nel.org>, linux-rockchip@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: rockchip: Add dma-names to uart1 on
 quartz64-b

On 2024-06-28 14:00, Diederik de Haas wrote:
> There have been several attempts to set the dma-names property on the
> SoC level (in rk356x.dtsi), but that appears to cause problems when set
> on channels without flow control.
> 
> Quoting part of a previous attempt for clarification:
> 
>> Nah, enabling it for bluetooth is fine because you have flow control.
>> My issues have been on channels without flow control. Without DMA it
>> simply drops messages or the channel hangs until you close and reopen
>> it. With DMA, when an overflow locks up the channel it is usually
>> unavailable until the board is rebooted.
> 
> Setting it on the board level for the bluetooth connection was deemed
> safe, so do so for the Quartz64 Model B.
> 
> This fixes the following error/warning:
> 
>   of_dma_request_slave_channel: dma-names property of node
>       '/serial@...50000' missing or empty
>   dw-apb-uart fe650000.serial: failed to request DMA
> 
> Signed-off-by: Diederik de Haas <didi.debian@...ow.org>
> Link: https://libera.irclog.whitequark.org/armlinux/2024-02-29
> Link: https://lore.kernel.org/linux-rockchip/18284546.sWSEgdgrri@diego/

Thanks for this patch, it's looking good to me.

Reviewed-by: Dragan Simic <dsimic@...jaro.org>

> ---
>  arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts
> b/arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts
> index b908ce006c26..13e599a85eb8 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts
> @@ -652,6 +652,7 @@ &tsadc {
>  };
> 
>  &uart1 {
> +	dma-names = "tx", "rx";
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&uart1m0_xfer &uart1m0_ctsn &uart1m0_rtsn>;
>  	status = "okay";