[EXT] Re: [RFC] usb: xhci: Some USB devices fail to initialize

[Elena Popa]

> > We've noticed that, at least, on the i.MX8M* platforms
> 
> Which exact platforms, which SoC, which board ?

Currently I'm testing on the i.MX8M Plus EVK. 
> 
> > , some USB devices (especially USB2.0 sticks) fail
> 
> Which exact sticks ? USB IDs and model would be helpful.

The stick is from EBV Generic Flash Disk, VID: 0x058f PID: 0x6387
> 
> Which U-Boot version is this ?

The 2 errors I already listed appears using the U-Boot v2023.04. 

Now I also tested on the v2024.04. These are the 3 behaviors:
- USB device fails to init with the error: "Device not responding to set address" 
- USB device fails to init with the error: "Cannot read configuration, skipping device 058f:6387"
- USB device succeeded to init with the following output:
scanning bus usb at 38200000 for devices... WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
WARN endpoint is halted
2 USB Device(s) found
       scanning usb for storage devices... 1 Storage Device(s) found

The succeeded initialization is very random. Sometimes it works, sometimes not.

Looking at the commits, I saw some improvements in the xHCI driver, but still, this issue remains.

I also tried the quick fix of adding the 5ms delay for v2024.04, and it's working: the USB device succeeded to initialize every time.

Thanks,
Elena