From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from qw-out-2122.google.com (qw-out-2122.google.com [74.125.92.25]) by ozlabs.org (Postfix) with ESMTP id 52ED7DDDF4 for ; Tue, 7 Oct 2008 07:41:22 +1100 (EST) Received: by qw-out-2122.google.com with SMTP id 9so672543qwb.15 for ; Mon, 06 Oct 2008 13:41:20 -0700 (PDT) Message-ID: <48EA77EF.6080502@genesi-usa.com> Date: Mon, 06 Oct 2008 15:41:19 -0500 From: Matt Sealey MIME-Version: 1.0 To: avorontsov@ru.mvista.com Subject: Re: [PATCH] pata_of_platform: fix no irq handling References: <20081006172653.GA26427@oksana.dev.rtsoft.ru> In-Reply-To: <20081006172653.GA26427@oksana.dev.rtsoft.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Sender: Matt Sealey Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Li Yang , Jeff Garzik , Wang Jian List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , There is a simple problem with the patch which is that an "IRQ 0" can and does actually exist on a bunch of platforms, at least to the best of my knowledge. Checking for -1 (which means for definite, no irq at all, because it is totally unambiguous, as a -1 IRQ numbering is "impossible") is more correct. The problem is the check against an unsigned value for interrupts (is there any reason why you would need 4 billion interrupts possible instead of just 2 billion?) although I must say, the patch will work, and probably 99.9999999% of people will never see a problem with it :) -- Matt Sealey Genesi, Manager, Developer Relations Anton Vorontsov wrote: > When no irq specified the pata_of_platform fills the 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; > 2. pata_platform checks for irq_res.start > 0, but since irq_res.start > is unsigned type, the check will be true for `-1'. > > Reported-by: Steven A. Falco > Signed-off-by: Anton Vorontsov > --- > > Resending again... > > drivers/ata/pata_of_platform.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/ata/pata_of_platform.c b/drivers/ata/pata_of_platform.c > index 408da30..1f18ad9 100644 > --- a/drivers/ata/pata_of_platform.c > +++ b/drivers/ata/pata_of_platform.c > @@ -52,7 +52,7 @@ static int __devinit pata_of_platform_probe(struct of_device *ofdev, > > ret = of_irq_to_resource(dn, 0, &irq_res); > if (ret == NO_IRQ) > - irq_res.start = irq_res.end = -1; > + irq_res.start = irq_res.end = 0; > else > irq_res.flags = 0; >