[BPI R2 PRO] cannot see uart9 device node

Joe_Culler · July 31, 2023, 2:47pm

Hello,

I tried to connect a uart device via 40-pin gpio (uart9_tx and uart9_rx) but doesn’t work. In rk3568-bpi-r2-pro.dts device tree, changed status to okay in

github.com

torvalds/linux/blob/master/arch/arm64/boot/dts/rockchip/rk3568-bpi-r2-pro.dts#L785


&uart7 {
	/* pin 11 (TX) + 13 (RX) of header con2 */
	pinctrl-0 = <&uart7m1_xfer>;
	status = "disabled";
};


&uart9 {
	/* pin 21 (TX) + 24 (RX) of header con2 */
	/* shared with pwm13 and pwm12/spi3 */
	pinctrl-0 = <&uart9m1_xfer>;
	status = "disabled";
};


&usb_host0_ehci {
	status = "okay";
};


&usb_host0_ohci {
	status = "okay";
};

After rebooting the machine, I cannot see the /dev/ttyS9 device node. Does anyone know how to fix it? Thanks.

frank-w · July 31, 2023, 3:05pm

uart9 is not mapped to ttyS9

Look for adress of uart9 in dtsi and search this in dmesg then there should be an entry with ttySx. If not try to increase the max uarts in your kernel

github.com

torvalds/linux/blob/master/arch/arm64/boot/dts/rockchip/rk356x.dtsi#L1448


		clocks = <&cru SCLK_UART8>, <&cru PCLK_UART8>;
		clock-names = "baudclk", "apb_pclk";
		dmas = <&dmac0 16>, <&dmac0 17>;
		pinctrl-0 = <&uart8m0_xfer>;
		pinctrl-names = "default";
		reg-io-width = <4>;
		reg-shift = <2>;
		status = "disabled";
	};


	uart9: serial@fe6d0000 {
		compatible = "rockchip,rk3568-uart", "snps,dw-apb-uart";
		reg = <0x0 0xfe6d0000 0x0 0x100>;
		interrupts = <GIC_SPI 125 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&cru SCLK_UART9>, <&cru PCLK_UART9>;
		clock-names = "baudclk", "apb_pclk";
		dmas = <&dmac0 18>, <&dmac0 19>;
		pinctrl-0 = <&uart9m0_xfer>;
		pinctrl-names = "default";
		reg-io-width = <4>;
		reg-shift = <2>;

So address is fe6d0000 and should visible in dmesg if device is probed successfully.

After fixing your link to dts i see my comment that uart9 is pin-shared with pwm13 and pwm12/spi3…have you disabled these nodes?

Joe_Culler · August 1, 2023, 5:02am

@frank-w Thank you very much for your help. After increasing the max uarts, I can see that device node.