Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751432AbWJMBBX (ORCPT ); Thu, 12 Oct 2006 21:01:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751433AbWJMBBX (ORCPT ); Thu, 12 Oct 2006 21:01:23 -0400 Received: from gate.crashing.org ([63.228.1.57]:34723 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S1751432AbWJMBBW (ORCPT ); Thu, 12 Oct 2006 21:01:22 -0400 Subject: Re: [linux-pm] Bug in PCI core From: Benjamin Herrenschmidt To: Alan Stern Cc: Greg KH , linux-pci@atrey.karlin.mff.cuni.cz, Linux-pm mailing list , Kernel development list In-Reply-To: References: Content-Type: text/plain Date: Fri, 13 Oct 2006 11:01:03 +1000 Message-Id: <1160701263.4792.179.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1113 Lines: 25 On Wed, 2006-10-11 at 16:41 -0400, Alan Stern wrote: > When a PCI device is suspended, its driver calls pci_save_state() so that > the config space can be restored when the device is resumed. Then the > driver calls pci_set_power_state(). > > However pci_set_power_state() calls pci_block_user_cfg_access(), and that > routine calls pci_save_state() again. This overwrites the saved state > with data in which memory, I/O, and bus master accesses are disabled. As > a result, when the device is resumed it doesn't work. > > Obviously pci_block_user_cfg_access() needs to be fixed. I don't know the > right way to fix it; hopefully somebody else does. Well, blocking user cfg access snapshots the config space to be able to respond to user space while the device is offline. Maybe it should be done from a separate config space image buffer ? ugh.... Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/