linux-kernel - Re: [PATCH] ata: Don't use NO_IRQ in pata_of

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Date:	Sat, 03 Dec 2011 10:12:53 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Dave Martin <dave.martin@...aro.org>,
	Anton Vorontsov <cbouatmailru@...il.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	devicetree-discuss@...ts.ozlabs.org,
	LKML <linux-kernel@...r.kernel.org>, linux-ide@...r.kernel.org,
	Randy Dunlap <rdunlap@...otime.net>,
	linux-next@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Jeff Garzik <jgarzik@...hat.com>,
	Pawel Moll <pawel.moll@....com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] ata: Don't use NO_IRQ in pata_of_platform driver

On Fri, 2011-12-02 at 11:28 -0800, Linus Torvalds wrote:
> On Fri, Dec 2, 2011 at 11:26 AM, Dave Martin <dave.martin@...aro.org> wrote:
> >
> > This is now broken on ARM where, for good or bad, NO_IRQ currently is
> > used and is -1.
> >
> > How do we resolve it?  If we are ready to eliminate NO_IRQ from
> > drivers/of/irq.c (or indeed, all code that uses it) and just use 0 for
> > that case, we should surely just do it... but I'm not confident I can
> > judge on that.
> 
> Just stop using NO_IRQ. First in drivers/of/irq.c, then in any drivers
> as you notice breakage.

Agreed. In fact the whole hack in drivers/of/irq.c was to accomodate ARM
which still uses -1, powerpc changed to 0 a long time ago.

Now that we have a generic remapper between HW and "linux" IRQ numbers,
there is no reason to stick to -1 even on ARM.

> Don't *change* NO_IRQ to zero (that whole #define is broken - leave it
> around as a marker of brokenness), just start removing it from all the
> ARM drivers that use the OF infrastructure. Which is presumably not
> all that many yet.
> 
> So whenever you find breakage, the fix now is to just remove NO_IRQ
> tests, and replace them with "!irq".

Cheers,
Ben.


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