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From:   Lukasz Majewski <lukma@denx.de>
To:     linux-kernel@vger.kernel.org, Shawn Guo <shawnguo@kernel.org>
Cc:     devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Mark Rutland <mark.rutland@arm.com>,
        Rob Herring <robh+dt@kernel.org>,
        Stefan Agner <stefan@agner.ch>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Lukasz Majewski <lukma@denx.de>
Subject: [PATCH] dts: Disable DMA support on the BK4 vf610 device's fsl_lpuart driver
Date:   Wed,  9 Oct 2019 16:30:32 +0200
Message-Id: <20191009143032.9261-1-lukma@denx.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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 = "","";
 	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";
 };
 
-- 
2.20.1