I want to agree with the reporter that U-Boot USB detection is unreliable, at
least for certain hardware. However the reporter probably needs to be more
specific about any messages displayed or if/where U-Boot is stuck, and what
devices are affected (USB vendor and device IDs).
In my case I am using U-Boot from recent openSUSE on Raspberry Pi 3 Model B,
and certain USB PATA bridges such as 0c0b:b311 initially fail to be detected
("usb_new_device: Cannot read configuration, skipping device 0c0b:b311"). The
workaround I use at the moment is to enter `usb reset` at the command prompt
until the drive is detected, and then I can `boot` into GRUB2.
