Messages in this thread | | | Date | Tue, 21 Aug 2012 15:50:09 +0100 | From | Mark Brown <> | Subject | Re: [RFC/PATCH 4/4] gpio: smscece: Add support for gpio IO expander feature |
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On Tue, Aug 21, 2012 at 03:22:18PM +0300, Felipe Balbi wrote: > On Tue, Aug 21, 2012 at 05:50:28PM +0530, Poddar, Sourav wrote:
> > If I am understanding correctly, if they both uses the same bit we cannot > > use both for a particular user. ?
> we can, it's just a bit more complex. If a user request both LOW and > HIGH, then you start with HIGH, once it triggers, before calling the > nested IRQ handler, you need to change it LOW. When low triggers, before > calling the nested IRQ handler, you need to change it to HIGH again. And > so on. I'm just not sure if that's valid on linux IRQ subsystem.
The given example was for keypress - usually a system would use edge triggered interrupts in combination with reading the GPIO state rather than level triggered interrupts.
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