Hi Jacky, Sending to the list as well. On Tue, Mar 1, 2011 at 1:55 AM, Jacky Lam <lamshuyin@xxxxxxxxx> wrote: > Hi, > > It's long before when I want to enable/disable an interrupt, I call > enable_irq()/disable_irq(). However, recently, I do that again. > disable_irq() do nothing. I looked into the code and find disable_irq() > is pointing to a empty function default_disable(). This change is > started from 2.6.20. > > I want to know what should I do if I want to disable an interrupt now? So disable/enable_irq are nestable, and you're expected to call them in the order disable/enable. You need to call enable_irq exactly the same number of times that you call disable_irq. If you start wth inerrtupts enabled and do enable_irq ...do some stuff... disable_irq then disable_irq will do nothing since it just decremented the count that enable_irq incremented. Another way of looking at it is that disable_irq increments a count, and enable_irq decrements a count. The interrupt is only "really" disabled when the count transitions from 0 to 1, and the interrupt is only "really" enabled when the count transitions from 1 to 0. Dave Hylands _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
