request_irq与request_threaded_irq

/*
* Allocate the IRQ
*/
#if 0
retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
#else
retval = request_threaded_irq(uap->port.irq, NULL, pl011_int, IRQ_TYPE_NONE | IRQF_ONESHOT,
"uart-pl011", uap);