Removal Of usb_add
This one irks me. usb_add was really simple to use to add a USB device. All you needed to know was the vendor and product ID.
It has been removed and device_add is now required. To add a device, you now need to the bus, host bus, and host address of the USB device.
As an example, say you have the following device (using lsusb):
Bus 001 Device 012: ID 18d1:4ee1 Google Inc. Nexus Device (MTP)
You will need to add it with this long winded command:
Or something similar to that.