[linux-usb-devel] Re: RE : MPC5200Lite PCI & IRQ

[David Woodhouse]

On Sat, 2004-06-26 at 15:02 +0100, Alan Cox wrote:
> There are a lot of drivers that assume 0 means no IRQ, including some
> big x86 non-PC systems. Remember however that dev->irq is an OS private
> cookie. In the x86 case for example we add 16 to APIC directed
> interrupts both to split IRQs out and to avoid this problem.

There aren't _that_ many drivers which have this bug; certainly not
non-ISA drivers. Even when you consider irq_t to be an OS-private
cookie, that doesn't excuse this brokenness on the part of drivers --
they need fixing.

> So if your board has an IRQ 0 and it is a problem - just change your
> numbering scheme.

That's a workaround, not a fix. Not really Linux style.

Personally, I think we want to stop even thinking of it as a numbering
scheme. IRQs are a tree, not a flat array.

--
dwmw2


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/