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SubjectRe: [PATCH/RFC] hardware irq debouncing support
On Wed 2008-09-24 12:51:32, David Brownell wrote:
> Hardware IRQ debouncing is common for IRQ controllers which are
> part of GPIO modules ... they often deal with mechanical switches,
> buttons, and so forth. This patch:
>
> - Provides simple support for that in genirq
>
> - Includes sample implementations for some Linux systems
> which already include non-generic support for this:
>
> * Atmel SOCs (AT91, AT32 -- the same GPIO module)
> * OMAP2/OMAP3 (not quite as simple)
>
> Control over how long to debounce is less common, and often applies
> to banks of GPIOs not individual signals ... not addressed here.
>
> Drivers can request this (where available) with a new IRQF_DEBOUNCED
> flag/hint passed to request_irq():
>
> IF that flag is set when a handler is registered
> AND the relevant irq_chip supports debouncing
> AND the IRQ isn't already flagged as being debounced
> THEN the irq_chip is asked to enable debouncing for this IRQ
> UNTIL the IRQ's last handler is unregistered.
> ELSE
> nothing is done ... the hint is ignored
> FI
>
> Comments?

How is this going to work with shared interrupt lines? If one handler
wants debouncing and second handler does not, you'll loose interrupts
for second handler?

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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