[PATCH v2] dts: Disable DMA support on the BK4 vf610 device's fsl_lpuart driver

[PATCH v2] dts: Disable DMA support on the BK4 vf610 device's fsl_lpuart driver

[Lukasz Majewski]

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>
Suggested-by: Robin Murphy <robin.murphy@arm.com>

---
Changes for v2:
- Use /delete-property/dma-names; instead of dma-names = "","";
---
 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..830c85476b3d 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>;
+	/delete-property/dma-names;
 	status = "okay";
 };
 
 &uart1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_uart1>;
+	/delete-property/dma-names;
 	status = "okay";
 };
 
 &uart2 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_uart2>;
+	/delete-property/dma-names;
 	status = "okay";
 };
 
 &uart3 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_uart3>;
+	/delete-property/dma-names;
 	status = "okay";
 };
 
-- 
2.20.1

Re: [PATCH v2] dts: Disable DMA support on the BK4 vf610 device's fsl_lpuart driver

[Shawn Guo]

On Thu, Oct 10, 2019 at 11:08:02AM +0200, 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>
> Suggested-by: Robin Murphy <robin.murphy@arm.com>

Subject prefix should be 'ARM: dts: ...'.  I fixed it up and applied the
patch.

Shawn

Re: [PATCH v2] dts: Disable DMA support on the BK4 vf610 device's fsl_lpuart driver

[Lukasz Majewski]

[-- Attachment #1: Type: text/plain, Size: 922 bytes --]

Hi Shawn,

> On Thu, Oct 10, 2019 at 11:08:02AM +0200, 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>
> > Suggested-by: Robin Murphy <robin.murphy@arm.com>  
> 
> Subject prefix should be 'ARM: dts: ...'.  I fixed it up and applied
> the patch.
> 
> Shawn

Thanks :-)


Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
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Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de

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