Re: [PATCH v3] uio/pdrv_genirq: Add OF support

[Scott Wood]

On Wed, 20 Apr 2011 00:00:18 +0200
"Hans J. Koch" <hjk@xxxxxxxxxxxx> wrote:

> On Tue, Apr 19, 2011 at 12:08:16AM -0600, Grant Likely wrote:
> > PowerPC and x86 will return 0 for an unassigned IRQ, as will most platforms.
> 
> That might be right for these architectures. On ARM SoCs, IRQ0 is often a
> normal irq like any other (e.g. "Audio DMA Controller 1" on Telechips TCC8000).

It's true on at least some powerpc and x86 interrupt controllers as well.
ARM isn't special. :-)

I'm not sure what goes on on x86, as I see a real " 0:" in
/proc/interrupts.  But on powerpc, Linux's IRQ numberspace is decoupled
from that of any IRQ controller.  This is mainly to accommodate multiple
IRQ controllers with their own numberspaces in the same system; being able
to avoid irq 0 is just a bonus.

-Scott

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