Message-ID: <4B292DA9.8040009@grandegger.com>
Date: Wed, 16 Dec 2009 19:57:45 +0100
From: Wolfgang Grandegger <wg@grandegger.com>
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To: =?ISO-8859-1?Q?Uwe_Kleine-K=F6nig?= 
	<u.kleine-koenig@pengutronix.de>
CC: linux-kernel@vger.kernel.org, David Vrabel <dvrabel@arcom.com>,
       Greg Kroah-Hartman <gregkh@suse.de>,
       Urs Thuermann <urs.thuermann@volkswagen.de>,
       Oliver Hartkopp <oliver.hartkopp@volkswagen.de>,
       "David S. Miller" <davem@davemloft.net>,
       Kurt Van Dijck <kurt.van.dijck@eia.be>, netdev@vger.kernel.org
Subject: Re: [PATCH 4/7] can/at91: don't check platform_get_irq's return	value
 against zero
References: <1260979809-24811-1-git-send-email-u.kleine-koenig@pengutronix.de> <1260979809-24811-2-git-send-email-u.kleine-koenig@pengutronix.de> <1260979809-24811-3-git-send-email-u.kleine-koenig@pengutronix.de> <1260979809-24811-4-git-send-email-u.kleine-koenig@pengutronix.de> <4B290A57.3010705@grandegger.com> <20091216170802.GA26325@pengutronix.de>
In-Reply-To: <20091216170802.GA26325@pengutronix.de>
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Uwe Kleine-K?nig wrote:
> On Wed, Dec 16, 2009 at 05:27:03PM +0100, Wolfgang Grandegger wrote:
>> Uwe Kleine-K?nig wrote:
>>> platform_get_irq returns -ENXIO on failure, so !irq was probably
>>> always true.  Better use (int)irq <= 0.  Note that a return value of
>>> zero is still handled as error even though this could mean irq0.
>> But only on ARM, which is the only platform still using the infamous
>> NO_IRQ (=-1). As this is a driver for ARM hardware, using irq == NO_IRQ
>> would make sense, though.
> 
> This has nothing to do with NO_IRQ.  You could do:

Right, sorry for the noise.

> -       if (!res || !irq) {
> +       if (!res || irq <= (int)NO_IRQ) {
> 
> but this looks too ugly.  (IMHO using NO_IRQ is already ugly.)
> 
> Still, before my patch platform_get_irq return 0 was an error and if
> this should be handled as irq0 this is a separate issue that should be
> fixed in a separate patch.

"irq <= 0" seems then the best solution. Will add my signed-off-by to
the patch.

Thanks,

Wolfgang.
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