Re: [PATCH 1/1] arm: omap: gpio: define .disable callback for gpio irq chip

[Eduardo Valentin <eduardo.valentin@nokia.com>]

Hello Russell,

On Wed, Jan 05, 2011 at 06:19:18PM +0000, Russell King wrote:
> On Wed, Jan 05, 2011 at 07:58:03PM +0200, Eduardo Valentin wrote:
> > Currently, if one calls disable_irq(gpio_irq), the irq
> > won't get disabled.
> > 
> > This is happening because the omap gpio code defines only
> > a .mask callback. And the default_disable function is just
> > a stub. The result is that, when someone calls disable_irq
> > for an irq in a gpio line, it will be kept enabled.
> > 
> > This patch solves this issue by setting the .disable
> > callback to point to the same .mask callback.
> 
> Amd this is a problem because?

errr.. because the interrupt is enabled when it was supposed to be disabled?

> 
> The way this works is that although it isn't disabled at that point,
> if it never triggers, then everything remains happy.  However, if it
> does trigger, the genirq code will then mask the interrupt and won't
> call the handler.

Right.. I didn't see from this point. I will check how that gets unmasked.
But even so, if I understood correctly what you described, it would still
open a time window which the system would see at least 1 interrupt during
the time it was not suppose to. And that can wakeup a system which  is in
deep sleep mode, either via dynamic idle or static suspend.

It is unlikely, I know. But it can still happen. And can be avoided.

Regards,

-- 
Eduardo Valentin