[PATCH 2/3] Fix irq flow handler for 4xx UIC

[Josh Boyer]

On Tue, 14 Aug 2007 13:52:42 +1000 (EST)
David Gibson <david at gibson.dropbear.id.au> wrote:

> At present the driver for the UIC (the embedded interrupt controller
> in 4xx chips) uses the handle_level_irq() flow handler.  It turns out
> this does not correctly handle level triggered interrupts on the UIC.
> 
> Specifically, acknowledging an irq on the UIC (i.e. clearing the
> relevant bit in UIC_SR) will have no effect for a level interrupt
> which is still asserted by the external device, even if the irq is
> already masked.  Therefore, unlike handle_level_irq() we must ack the
> interrupt after invoking the ISR (which should cause the device to
> stop asserting the irq) instead of acking it when we mask it, before
> the ISR.
> 
> This patch implements this change, in a new handle_uic_irq(), a
> customised irq flow handler for the UIC.  For edge triggered
> interrupts, handle_uic_irq() still uses the old flow - we must ack
> edge triggered interrupt before the ISR not after, or we could miss a
> second event which occurred between invoking the ISR and acking the
> irq.
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Acked-by: Josh Boyer <jwboyer at linux.vnet.ibm.com>

josh