irq
Undoes the effect of one call to disable_irq. If this matches the last disable, processing of interrupts on this IRQ line is re-enabled.
This function may be called from IRQ context only when desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
Thomas Gleixner <tglx@linutronix.de>
Ingo Molnar <mingo@elte.hu>