Re: [RFC/PATCH 4/4] gpio: smscece: Add support for gpio IO expander feature
From: Mark Brown <hidden>
Date: 2012-08-21 14:50:16
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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:
quoted
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.