Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754533Ab0AZRco (ORCPT ); Tue, 26 Jan 2010 12:32:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753996Ab0AZRcn (ORCPT ); Tue, 26 Jan 2010 12:32:43 -0500 Received: from g4t0015.houston.hp.com ([15.201.24.18]:20517 "EHLO g4t0015.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753177Ab0AZRcm (ORCPT ); Tue, 26 Jan 2010 12:32:42 -0500 From: Bjorn Helgaas To: "Rafael J. Wysocki" Subject: Re: [Bug #15124] PCI host bridge windows ignored (works with pci=use_crs) Date: Tue, 26 Jan 2010 10:32:35 -0700 User-Agent: KMail/1.9.10 Cc: Jeff Garrett , Yinghai Lu , Linux Kernel Mailing List , Kernel Testers List , Linux PCI , Linus Torvalds , Jesse Barnes , Myron Stowe , Matthew Garrett , Ingo Molnar References: <20100126071912.GA7543@jgarrett.org> <201001261348.59508.rjw@sisk.pl> In-Reply-To: <201001261348.59508.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201001261032.37053.bjorn.helgaas@hp.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2683 Lines: 60 On Tuesday 26 January 2010 05:48:59 am Rafael J. Wysocki wrote: > On Tuesday 26 January 2010, Jeff Garrett wrote: > > On Sun, Jan 24, 2010 at 11:04:38PM +0100, Rafael J. Wysocki wrote: > > > The following bug entry is on the current list of known regressions > > > from 2.6.32. Please verify if it still should be listed and let me know > > > (either way). > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=15124 > > > Subject : PCI host bridge windows ignored (works with pci=use_crs) > > > Submitter : Jeff Garrett > > > Date : 2010-01-13 5:37 (12 days old) > > > References : http://marc.info/?l=linux-kernel&m=126336296600307&w=4 > > > Handled-By : Yinghai Lu > > > Bjorn Helgaas > > > > This regression should still be listed. No patch to test yet. > ... > IIRC, we already know how to fix this ... As far as I know, we do NOT know how to fix this. This regression occurred when we added intel_bus.c because it's not yet smart enough to determine the correct host bridge apertures. Here's what it thinks the bridge aperture is and the Radeon BAR: IOH bus: 00 index 1 mmio: [e0000000, fdffffff] pci 0000:04:00.0: reg 10: [mem 0xd0000000-0xdfffffff 64bit pref] The IOH aperture is obviously not big enough to cover the Radeon BAR. But the host bridge _CRS tells us this: pci_root PNP0A08:00: host bridge window [mem 0xc0000000-0xdfffffff] pci_root PNP0A08:00: host bridge window [mem 0xf0000000-0xfed8ffff] which IS big enough, and we know the bridge is in fact forwarding the [mem 0xd0000000-0xdfffffff 64bit pref] region, because the Radeon works when Jeff boots with "pci=use_crs". I'm quite concerned about this for .33 because I don't think Jeff's configuration (Dell desktop with Intel x58 and large graphics device) is unusual. The benefit of intel_bus.c is on machines with multiple IOHs, where we need to figure out which address ranges go to which IOHs so we can program downstream devices correctly. But even there, _CRS should give us the information we need, so "pci=use_crs" should make these machines work. I think we should remove intel_bus.c before .33. It's breaking boxes and we don't know how to fix it. Even if we do find out how to fix it, I think we should move toward using _CRS instead, because that's what Windows uses and it's an easy way for the firmware to tell us about platform quirks. Bjorn -- 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/