UART3 & 4 are both RS485 ports.
So we need to configure and enable this by default.

Signed-off-by: Mark Jackson <mpfj@newflow.co.uk>
---
 arch/arm/boot/dts/am335x-nano.dts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm/boot/dts/am335x-nano.dts b/arch/arm/boot/dts/am335x-nano.dts
index 05cbfe24f778..cecc2afaeff4 100644
--- a/arch/arm/boot/dts/am335x-nano.dts
+++ b/arch/arm/boot/dts/am335x-nano.dts
@@ -187,12 +187,22 @@ &uart2 {
 &uart3 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&uart3_pins>;
+	rts-gpio = <&gpio2 17 GPIO_ACTIVE_HIGH>;
+	rs485-rts-active-high;
+	rs485-rx-during-tx;
+	rs485-rts-delay = <1 1>;
+	linux,rs485-enabled-at-boot-time;
 	status = "okay";
 };
 
 &uart4 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&uart4_pins>;
+	rts-gpio = <&gpio0 9 GPIO_ACTIVE_HIGH>;
+	rs485-rts-active-high;
+	rs485-rx-during-tx;
+	rs485-rts-delay = <1 1>;
+	linux,rs485-enabled-at-boot-time;
 	status = "okay";
 };
 
-- 
2.34.1