From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anton Vorontsov Subject: [PATCH] pata_of_platform: fix no irq handling Date: Mon, 11 Aug 2008 19:19:13 +0400 Message-ID: <20080811151913.GA14690@oksana.dev.rtsoft.ru> References: <48A05152.7020508@harris.com> Reply-To: avorontsov@ru.mvista.com Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <48A05152.7020508@harris.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linuxppc-dev-bounces+glppd-linuxppc64-dev=m.gmane.org@ozlabs.org Errors-To: linuxppc-dev-bounces+glppd-linuxppc64-dev=m.gmane.org@ozlabs.org To: Jeff Garzik , "Steven A. Falco" Cc: linuxppc-dev@ozlabs.org, linux-ide@vger.kernel.org List-Id: linux-ide@vger.kernel.org When no irq specified, pata_of_platform fills 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 --- On Mon, Aug 11, 2008 at 10:48:50AM -0400, Steven A. Falco wrote: > I think there is a bug in the communications between pata_of_platform > and pata_platform. I will refer to the master branch of the DENX git > tree, which is roughly v2.6.26.1 at this time. I am using a Sequoia > board with a PPC440EPx. > > In pata_of_platform, we have: > > ret = of_irq_to_resource(dn, 0, &irq_res); > if (ret == NO_IRQ) > irq_res.start = irq_res.end = -1; > > so if there is no interrupt defined, then start and end are -1. > However, __pata_platform_probe has: > > if (irq_res && irq_res->start > 0) { > irq = irq_res->start; > irq_flags = irq_res->flags; > } > > You might think that the (irq_res->start > 0) test will fail, as it > should in this no-irq case. But, start is a u64, so the -1 actually > looks like a large positive number in the comparison. So, > __pata_platform_probe attempts to use an interrupt when there isn't one. > > I think the fix would be to change __pata_platform_probe to: > > if (irq_res && irq_res->start != -1) { > > but that might have other unintended consequences, so I'll defer to > whomever knows more about the intent of this code. Something like this patch should work. Thanks for noticing! 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; -- 1.5.6.3