From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King Subject: Re: [PATCH/RFC] PCI prepare/activate instead of enable to avoid IRQ storm and rogue DMA access Date: Wed, 14 Mar 2007 21:56:06 +0000 Message-ID: <20070314215605.GA7194@flint.arm.linux.org.uk> References: <20070314152302.GB15600@htj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from caramon.arm.linux.org.uk ([217.147.92.249]:2801 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422678AbXCNV4a (ORCPT ); Wed, 14 Mar 2007 17:56:30 -0400 Content-Disposition: inline In-Reply-To: <20070314152302.GB15600@htj.dyndns.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: gregkh@suse.de, Jeff Garzik , linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, michal.k.k.piotrowski@gmail.com, linux-ide@vger.kernel.org, tglx@linutronix.de, shemminger@linux-foundation.org, mlord@pobox.com, linux-pm@lists.osdl.org On Thu, Mar 15, 2007 at 12:23:02AM +0900, Tejun Heo wrote: > The problem is that a PCI device can be in any arbitrary when it gets > enabled and the device has to be enabled for its driver to > initialize/reset it. The most common case this causes headache is as > follows. > > Let's assume there's a device which shares its INTX IRQ line with > another device and the other one is already initialized. pci_enable_device() doesn't deal with this; in most PCI setups I've seen, there is no control at PCI level over whether a device generates an interrupt on the bus. Certainly the memory and io command enables have no effect on the ability of the device to cause an interrupt. In most cases, only the driver of the device knows how to disable interrupts on any particular device. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: