Date: Mon, 23 Jun 2008 10:08:23 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: David Brownell <david-b@pacbell.net>
Cc: lkml <linux-kernel@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
       Ingo Molnar <mingo@elte.hu>, hpa@zytor.com
Subject: Re: [patch] x86 supports NO_IRQ convention
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In-Reply-To: <200806221953.18849.david-b@pacbell.net>
References: <200806221953.18849.david-b@pacbell.net>
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On Sun, 22 Jun 2008 19:53:18 -0700
David Brownell <david-b@pacbell.net> wrote:

> Hmm, x86 doesn't seem to support the NO_IRQ convention.  This means
> that portable code can't use it.  Which in turn means that there's
> no portable way for drivers to know whether they have been handed a
> valid IRQ number (zero usually being valid).  Double-plus ungood.

NAK. It was discussed before repeatedly as you suspected and settled by
Linus ultimately.

Zero is not a valid IRQ in the kernel mapping of things. If you have a
physical IRQ 0 remap it. That way you can write the more natural

	if (dev->irq)
		setup_for_irq(dev);
	else
		poll(dev);

type stuff.

NO_IRQ was intentionally removed from various platforms and really wants
kicking out of some others.

Alan
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