Thanx Electro for your reply!
That's the problem. I just can't disconnect the device if something goes wrong (for example after a very short fault of power supply of a computer, addresses of usb devices may be lost. To reassign the address of a device, I found the only one solution, is to power the port off and then power it on back). I'm writing a software for embedded linux based system (telecommunication module), which must be automated as much as possible.
It is still experimental in the kernel.
Where can I read about this?