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From: Scott Wood <scottwood@freescale.com>
To: "Hans J. Koch" <hjk@hansjkoch.de>
Cc: Grant Likely <grant.likely@secretlab.ca>,
	devicetree-discuss@lists.ozlabs.org,
	linux-kernel@vger.kernel.org, john.williams@petalogix.com
Subject: Re: [PATCH v3] uio/pdrv_genirq: Add OF support
Date: Tue, 19 Apr 2011 18:09:19 -0500	[thread overview]
Message-ID: <20110419180919.17971598@schlenkerla.am.freescale.net> (raw)
In-Reply-To: <20110419220018.GB2772@local>

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

  reply	other threads:[~2011-04-19 23:09 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-18  8:50 [PATCH v3] uio/pdrv_genirq: Add OF support Michal Simek
2011-04-18 10:35 ` Paul Mundt
     [not found]   ` <20110418103513.GA27864-M7jkjyW5wf5g9hUCZPvPmw@public.gmane.org>
2011-04-18 11:10     ` Michal Simek
     [not found] ` <1303116654-5042-1-git-send-email-monstr-pSz03upnqPeHXe+LvDLADg@public.gmane.org>
2011-04-18 16:06   ` Wolfram Sang
     [not found]     ` <20110418160658.GD23814-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2011-04-19  1:58       ` John Williams
2011-04-19  6:11         ` Grant Likely
2011-04-19  7:32           ` Arnd Bergmann
     [not found]             ` <201104190932.31777.arnd-r2nGTMty4D4@public.gmane.org>
2011-04-19  8:42               ` Michal Simek
2011-04-19 12:37           ` John Williams
2011-04-19 13:02             ` Arnd Bergmann
2011-04-19 14:49             ` Grant Likely
2011-04-19 15:07               ` Arnd Bergmann
     [not found]                 ` <201104191707.40456.arnd-r2nGTMty4D4@public.gmane.org>
2011-04-19 15:45                   ` Grant Likely
     [not found]         ` <BANLkTimFnfgiQ5aMq_KwqHP8p92pjOJJwg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-04-21 12:08           ` Wolfram Sang
     [not found]             ` <20110421120855.GC2135-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2011-04-21 23:46               ` John Williams
2011-04-22  6:07                 ` Wolfram Sang
2011-04-19  8:16       ` Michal Simek
2011-04-19  6:08 ` Grant Likely
2011-04-19  8:15   ` Michal Simek
2011-04-19 22:00   ` Hans J. Koch
2011-04-19 23:09     ` Scott Wood [this message]
2011-04-27 11:05   ` Michal Simek

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