Re: [PATCH] Alchemy: fix edge irq handling

[Manuel Lauss <mano@roarinelk.homelinux.net>]

Hi Kevin,

> Have you actually seen this happen (outside of inducing it manually)?  I
> have some concern that by doing this we may either miss interrupts on
> devices that send a lot (by design) or miss a design bug in a system
> because we are masking out some interrupts.  I know that system
> stability is important, but I don't like hiding problems.

Yes, in a customer project.  A simple pushbutton which connects a pulled-up
gpio pin to ground.  Push it, instant hang (handler called over and over
again) when it is not debounced.  With a single edge and a much lower
edge-frequency it obviously works fine (see timer).

(And, handle_edge_irq() _does_ call mask_ack() after all).


Best regards,
	Manuel Lauss

 
> =Kevin
> 
> On Tue, 2009-01-20 at 11:03 +0100, Manuel Lauss wrote:
> > Introduce separate mack_ack callbacks which really do shut up the
> > edge-triggered irqs when called.  Without this change, high-frequency
> > edge interrupts can result in an endless irq storm, hanging the system.
> > 
> > This can be easily triggered for example by setting an irq to falling
> > edge type and manually connecting the associated pin to ground.
> >