tv_sec on smsc_at2

In 
void at2_read_buffer

tv.tv_sec = 0;

tv.tv_usec = 1000;

ret = select(privdata->fd + 1, &read_fd, NULL, NULL, &tv);

If I disconnect modem from serial the above select does not

return anything, at least in the 2 hours I waited :-)

So I'm wondering if anybody knows if we should change tv.tv_usec 

to something else than 1000 (seconds, minutes or what is this usec?)

Thanks

Andrea