Messages in this thread | | | Subject | Re: [PATCH] genirq: irq_chip->startup() usage in setup_irq and set_irq_chained handler | From | Pawel MOLL <> | Date | Tue, 26 Aug 2008 11:14:36 +0100 |
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> The second change is a significant semantic change. I wouldn't be > surprised if I have cases that rely (or work around) the lack of > startup() in set_irq_chained_handler(). I'll have to dbl check things > next week.
Let me briefly explain my situation. I have a main interrupt controller which provides startup() and unmask/mask() functions. The first one is rather expensive (as the controller itself is... hmmm... complicated ;-), the second - very cheap. And that is how I understand the different "levels" of interrupt access - startup() should be called once, somewhere during request_irq(), (un)masking may be used frequently.
And one of the interrupt is generated by hardware PIO controller. The idea was obvious - register a chained handler, which decodes the PIO controller state and generates a interrupt, which number may be obtained by gpio_to_irq(). Sounds simple, doesn't it? :-)
And in that moment the problem raised its ugly head - the interrupt controller's startup() was never called for the PIO interrupt (as there was no request_irq()), so the hardware wasn't configured properly and... well... bad things were happening ;-)
So unless I totally misunderstood the meaning of irq_chip callbacks, I believe the startup() should be called in set_irq_chained_handler().
Regards
Paweł
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