To whoever is receiving this, I hope you're doing well and healthy amidst this pandemic.
Currently, I'm running several FTDI (FT4232HL-REEL) chips on a board that's using a congatec QMX6 (https://www.congatec.com/us/products/qseven/conga-qmx6.html) module. I have reached out to Congatec but have yet to receive any useful information. This module runs i.MX6Q. This system is running minimal Linux OS v4.9.88 configured by Yocto. I've installed the usb serial drivers provided by linux (usb_serial, usb_serial_ftdi_sio, usb_serial_generic). I've attached the board schematic CPU_CarrierBoardRevA if you're interested.
Based on the board schematic, I'm currently testing J8 uart (COM1) that utilizes this FTDI chip. As I'm plugging in a TTL-232R-3V3 cable, serial end to the board and usb side to my windows 7 PC, the target Linux system does not register or see any device. No kernel printout/messages were displayed when the device plugs in. I also have the latest FTDI drivers for the PC (2.12.28).
The board has an additional 2 usb ports with connectors (USB0 & USB1 on schematic) that are separate from the interfaces using the on board FTDI chips. One of the usb connectors is routed to the OTG device. The second usb connector and the FTDI devices are routed to USB Hub 1. Please see the diagram below (from congatec QMX6 Software User Guide):
What I've Done:
I've configured the device tree for the Linux OS to enable USB Hub 1 and USB OTG. The two usb connectors (USB0/1) are working correctly as I can see the kernel printouts and the device being registered when I plug in to either ports. Since one USB device is working on Hub 1, it's safe to assume the hub is working properly.
I've also confirmed that Linux OS has the latest drivers for FTDI because I can plug the usb end of the TTL-232R-3V3 cable into either of those usb connector ports and it registers with the correct manufacturer and product information.
From my understanding there isn't any extra device tree configuration necessary besides enabling the hub. The usb drivers should take over when a device is connected to register it.
PLEASE NOTE: I've confirmed that these FTDI IC's hardware works by swapping the congatec-QMX6 module with a congatec-AG (x86) module on the same board and the FTDI ICs work perfectly fine.
Are USB2,3,4 disabled by default and need to be turned on via software somehow?
We are at a stand still on what to try next.