How can I power cycle a USB device on Raspberry Pi?
Solution 1:
If your USB host driver is compiled as a kernel module you can try to unload it and reload it. This should usually also power off totally the USB (I did it on other devices with faulty USB hardware that need to be electrically reset, not specifically on the Rasperry Pi which I don't have sorry). So check if you see it as a module (lsmod) or compile it as a module and later on rmmod it (and all the dependencies eventually) and reload it again, it should do the trick.