From mboxrd@z Thu Jan  1 00:00:00 1970
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH] pata_of_platform: fix no irq handling
Date: Tue, 12 Aug 2008 08:02:01 +1000
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To: Ben Dooks <ben-linux@fluff.org>
Cc: linuxppc-dev@ozlabs.org, Jeff Garzik <jgarzik@pobox.com>, linux-ide@vger.kernel.org
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On Mon, 2008-08-11 at 17:36 +0100, Ben Dooks wrote:
> On Mon, Aug 11, 2008 at 07:19:13PM +0400, Anton Vorontsov wrote:
> > When no irq specified, pata_of_platform fills irq_res with -1,
> > which is wrong to do for two reasons:
> > 
> > 1. By definition, 'no irq' should be IRQ 0, not some negative integer;

> interesting, IRQ 0 is actually valid on some ARM systems.

It never is on powerpc (anymore). Linus several times said he believed
that was the right thing to do, so when I make the whole IRQ handling
using virtual IRQ numbers on ppc, I made 0 reserved (and 1..15 only ever
assigned to a 8259 if there's one).

ARM, with their collections of cascaded fancy PICs all over the place
should probably look into using a similar remapping scheme :-)
 
Ben.