UART3 & 4 are both RS485 ports. So we need to configure and enable this by default. Signed-off-by: Mark Jackson <mpfj@xxxxxxxxxxxxx> --- 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