[PATCH 6/6] ARM: nmk: update GPIO chained IRQ handler to use EOI in parent chip

[tglx@linutronix.de (Thomas Gleixner)]

On Wed, 2 Mar 2011, Will Deacon wrote:

> Hi Thomas,
> 
> > Can you please take the time and explain me the difference of the
> > following:
> > 
> > irqchip1.c
> > 
> > struct irq_chip1;
> > 
> > handle_primary_irq(int irq, struct irq_desc *desc)
> > {
> > 	chip->irq_ack();
> > 	desc->demux();
> > }
> > 
> > init()
> > {
> > 	irq_set_chip(PRIMARY_IRQ, &irq_chip1);
> > 	irq_set_primary_handler(PRIMARY_IRQ, handle_primary_irq);
> > }
> 
> I think with this approach you get the exact opposite problem; that
> is the primary irq_chip doesn't know which IRQs are going to be
> demuxed so it cannot know at init time which IRQs need their primary 
> handler set. Is the idea that you set_primary_handler for all IRQs,
> stash that in the descriptor somewhere and then replace handle_irq
> with the primary handler when a demux handler is registered?
> 
> I guess I'm missing something here,

No, I missed that. Darn, yes this would need storing the
primary_handler in some separate pointer or having a callback into the
chip implementation to make this fully distangled.

Grmbl.

	tglx