UDC can work well for several times (insmod and rmmod for several
times) ,but it may not get descriptor of GET_DESCRIPTOR once or twice . and
the PC can not recognize the device .after that happens , it will repeat for
times( it never mind rmmod and insmod the module, or plug in or out
after set_config , epn can work well,but after several minutes correct
transfers(our process keep transfering for a long time) , our driver may get a
wrong state when get data from pc . the state is SHUTDOWN or OVERFLOW.
I want to know which the error is mostly
