From: Robin Murphy <robin.murphy@arm.com>
To: Lukasz Majewski <lukma@denx.de>,
linux-kernel@vger.kernel.org, Shawn Guo <shawnguo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org, Sascha Hauer <s.hauer@pengutronix.de>,
Stefan Agner <stefan@agner.ch>, Rob Herring <robh+dt@kernel.org>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] dts: Disable DMA support on the BK4 vf610 device's fsl_lpuart driver
Date: Wed, 9 Oct 2019 15:40:00 +0100 [thread overview]
Message-ID: <b39b6860-9e9b-5cee-a07e-7b430c2e5119@arm.com> (raw)
In-Reply-To: <20191009143032.9261-1-lukma@denx.de>
On 09/10/2019 15:30, Lukasz Majewski wrote:
> This change disables the DMA support (RX/TX) on the NXP's fsl_lpuart
> driver - the PIO mode is used instead. This change is necessary for better
> robustness of BK4's device use cases with many potentially interrupted
> short serial transfers.
>
> Without it the driver hangs when some distortion happens on UART lines.
>
> Signed-off-by: Lukasz Majewski <lukma@denx.de>
> ---
> arch/arm/boot/dts/vf610-bk4.dts | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm/boot/dts/vf610-bk4.dts b/arch/arm/boot/dts/vf610-bk4.dts
> index 0f3870d3b099..ad20f3442d40 100644
> --- a/arch/arm/boot/dts/vf610-bk4.dts
> +++ b/arch/arm/boot/dts/vf610-bk4.dts
> @@ -259,24 +259,28 @@
> &uart0 {
> pinctrl-names = "default";
> pinctrl-0 = <&pinctrl_uart0>;
> + dma-names = "","";
This looks like a horrible hack - is there any reason not to just strip
things at compile-time, i.e. "/delete-property/ dmas;"?
Robin.
> status = "okay";
> };
>
> &uart1 {
> pinctrl-names = "default";
> pinctrl-0 = <&pinctrl_uart1>;
> + dma-names = "","";
> status = "okay";
> };
>
> &uart2 {
> pinctrl-names = "default";
> pinctrl-0 = <&pinctrl_uart2>;
> + dma-names = "","";
> status = "okay";
> };
>
> &uart3 {
> pinctrl-names = "default";
> pinctrl-0 = <&pinctrl_uart3>;
> + dma-names = "","";
> status = "okay";
> };
>
>
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next prev parent reply other threads:[~2019-10-09 14:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 14:30 [PATCH] dts: Disable DMA support on the BK4 vf610 device's fsl_lpuart driver Lukasz Majewski
2019-10-09 14:40 ` Robin Murphy [this message]
2019-10-09 14:44 ` Lukasz Majewski
2019-10-09 15:15 ` Robin Murphy
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