Enabling usb host controller to detect ttyUSB0 for i.MX8MN

[betanapallisandeepraj]

Hi,

I am trying to connect a serial console to usb interface in i.MX8MN board with ddr4. SoM is i.MX8MN and base board is custom with USB connection to connect a serial device through the USB. When we connect to ubuntu host machine I could see my sensor detected with ttyUSB0. Similarly I would like to interface my sensor to i.MX8MN board with USB interface to read the data serially. I have enabled 2 configurations as below, 

CONFIG_USB_SERIAL_CONSOLE=y

CONFIG_USB_SERIAL_GENERIC=y

Solved: Enable ttyUSB0 - NXP Community

In device tree I could see usbotg1: usb@32e40000 and usbmisc1: usbmisc@32e40200 already. Is there any changes needed in the device tree to enable the usb to serial host support in the i.MX8MN SoM.

I could already see ttymxc0, ttymxc1, ttymxc2. I am using ttymxc2 for another application on bluetooth. I think ttymxc1 for serial debug console. Can I use ttymxc0, If I am not using M7 controller on the board?
If so, how to free it?

From kernel and device tree or bootloader do I need to add any other changes to support this usb serial interface feature on i.MX8MN SoM source code. Any suggestions on this would be very helpful. 

[betanapallisandeepraj · Accepted solution]

Hi,

To convert default usb otg in i.MX8mn to normal usb host only on the board, I have done below changes,

$pwd
/home/sandeepraj/imx-yocto-bsp1/build-wayland/tmp/work-shared/imx8mnevk/kernel-source/arch/arm64/boot/dts/freescale
$vim imx8mn-ddr4-evk.dts
&usbotg1 {
picophy,pre-emp-curr-control = <3>;
picophy,dc-vol-level-adjust = <7>;
// dr_mode = "otg";
dr_mode = "host";
hnp-disable;
srp-disable;
adp-disable;
// usb-role-switch;
status = "okay";
/*
port {
usb1_drd_sw: endpoint {
remote-endpoint = <&typec1_dr_sw>;
};
};
*/
};

/*
ptn5110_1: tcpc@50 {
compatible = "nxp,ptn5110";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_typec1>;
reg = <0x50>;
interrupt-parent = <&gpio2>;
interrupts = <11 8>;
status = "okay";

port {
typec1_dr_sw: endpoint {
remote-endpoint = <&usb1_drd_sw>;
};
};

typec1_con: connector {
compatible = "usb-c-connector";
label = "USB-C";
power-role = "dual";
data-role = "dual";
try-power-role = "sink";
source-pdos = <PDO_FIXED(5000, 3000, PDO_FIXED_USB_COMM)>;
sink-pdos = <PDO_FIXED(5000, 3000, PDO_FIXED_USB_COMM)
PDO_VAR(5000, 20000, 3000)>;
op-sink-microwatt = <15000000>;
self-powered;
};
};
*/
disable other serial drivers in usb support related serial or other to work.
In my case default serial driver did not work, so I enabled the required one. 

After doing all these changes along with serial baudrate configuration from my application, 
I could read my sensor data through the usb serial interface that is /dev/ttyUSB0. 

Thank you NXP for the support over email communication. 

[betanapallisandeepraj]

usb host controller is working fine with nxp board. but in the custom board we have removed the Power Management IC and changed the otg usb-c slot to USB host adapter slot in custom board. What are the changes required in device tree or kernel if we remove the PMIC with respect to usb device?