Khadas VIM3 contains a 2:1 data switch chipset to switch the “combo interface” between PCIe and USB 3.0, and the default mode is USB 3.0.

You need to setup the serial debug tool and enter the u-boot command line.

Initialize the KBI:

kvim3#kbi init

Check current port mode:

kvim3#kbi portmode r
port mode is USB3.0

The default mode is USB-3.0.

Change mode to PCIe:

kvim3#kbi portmode  w 1
set port mode to :PCIE

Change mode to USB 3.0:

kvim3#kbi portmode w 0
set port mode to :USB3.0

Poweroff the system to bring changes into effect:

kvim3#kbi poweroff 
do_kbi_poweroff

Then press the POWER KEY to boot the system

Check current port mode:

khadas@Khadas:~$ cat /sys/class/mcu/usb_pcie_switch_mode
1

0 - USB 3.0 mode 1 - PCIe mode

Change mode to USB 3.0:

khadas@Khadas:~$ echo 0 > /sys/class/mcu/usb_pcie_switch_mode

Change mode to PCIe:

khadas@Khadas:~$ echo 1 > /sys/class/mcu/usb_pcie_switch_mode

Poweroff the system to bring changes into effect:

khadas@Khadas:~$ echo 1 > /sys/class/mcu/poweroff 

Then press the POWER KEY to boot the system.