RS485 uart does not appear in /dev

Technical Support
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1

Hi,
I want to configure uart2 to operate in RS485 mode. Therefore i followed the instructions here and edited the device tree like show below. Unfortunately the /dev/ttymxc2 does not show up any more (it was there without modifications). Maybe i missed something? Thanks in advance.

imx6qdl-apalis.dtsi

&uart2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart2_dte>;
	fsl,dte-mode;
	uart-has-rtscts;
	status = "disabled";
};

imx6qdl-apalis-eval.dtsi

&uart2 {
	status = "okay";
        dma-names = "","";
	linux,rs485-enabled-at-boot-time;
	rs485-rts-active-low;
	rs485-rx-during-tx;
};

imx6qdl.dtsi

uart2: serial@021e8000 {
				compatible = "fsl,imx6q-uart", "fsl,imx21-uart";
				reg = <0x021e8000 0x4000>;
				interrupts = <0 27 IRQ_TYPE_LEVEL_HIGH>;
				clocks = <&clks IMX6QDL_CLK_UART_IPG>,
					 <&clks IMX6QDL_CLK_UART_SERIAL>;
				clock-names = "ipg", "per";
				dmas = <&sdma 27 4 0>, <&sdma 28 4 0>;
				dma-names = "rx", "tx";
				status = "disabled";
			};
2

You’ve set it to disabled.

3

The names were accidentally twisted. The uart2 is set to “okay” in the imx6qdl-apalis-eval.dtsi.

4

HI @qojote, So is it working now or not? If not, could you share your devicetree files? Thanks.

5

Hi,
No, its not working yet. Please find attached my devicetree files.link text

6

hi,
Thanks for the files. They seem to be Ok. Are you sure that you flashed the correct device tree file?
Could you provide the dmesg log and the output of ls /dev | grep ttymxc?
Thanks.