From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759979AbZADXgb (ORCPT ); Sun, 4 Jan 2009 18:36:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752475AbZADXf3 (ORCPT ); Sun, 4 Jan 2009 18:35:29 -0500 Received: from one.firstfloor.org ([213.235.205.2]:56837 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752123AbZADXf1 (ORCPT ); Sun, 4 Jan 2009 18:35:27 -0500 From: Andi Kleen References: <200901051236.281008835@firstfloor.org> In-Reply-To: <200901051236.281008835@firstfloor.org> To: akpm@linux-foundation.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] [1/5] Only scan the root bus in early PCI quirks. Message-Id: <20090104233638.60AF53E6653@basil.firstfloor.org> Date: Mon, 5 Jan 2009 00:36:38 +0100 (CET) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We found a situation on Linus' machine that the Nvidia timer quirk hit on a Intel chipset system. The problem is that the system has a fancy Nvidia card with an own PCI bridge, and the early-quirks code looking for any NVidia bridge triggered on it incorrectly. This didn't lead a boot failure by luck, but the timer routing code selecting the wrong timer first and some ugly messages. It might lead to real problems on other systems. I checked all the devices which are currently checked for by early_quirks and it turns out they are all located in the root bus zero. So change the early-quirks loop to only scan bus 0. This incidently also saves quite some unnecessary scanning work, because early_quirks doesn't go through all the non root busses. The graphics card is not on bus 0, so it is not matched anymore. Signed-off-by: Andi Kleen --- arch/x86/kernel/early-quirks.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) Index: linux-2.6.28-test/arch/x86/kernel/early-quirks.c =================================================================== --- linux-2.6.28-test.orig/arch/x86/kernel/early-quirks.c 2008-11-24 16:42:46.000000000 +0100 +++ linux-2.6.28-test/arch/x86/kernel/early-quirks.c 2008-12-29 05:25:09.000000000 +0100 @@ -200,6 +200,12 @@ void (*f)(int num, int slot, int func); }; +/* + * Only works for devices on the root bus. If you add any devices + * not on bus 0 readd another loop level in early_quirks(). But + * be careful because at least the Nvidia quirk here relies on + * only matching on bus 0. + */ static struct chipset early_qrk[] __initdata = { { PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, nvidia_bugs }, @@ -266,17 +272,17 @@ void __init early_quirks(void) { - int num, slot, func; + int slot, func; if (!early_pci_allowed()) return; /* Poor man's PCI discovery */ - for (num = 0; num < 32; num++) - for (slot = 0; slot < 32; slot++) - for (func = 0; func < 8; func++) { - /* Only probe function 0 on single fn devices */ - if (check_dev_quirk(num, slot, func)) - break; - } + /* Only scan the root bus */ + for (slot = 0; slot < 32; slot++) + for (func = 0; func < 8; func++) { + /* Only probe function 0 on single fn devices */ + if (check_dev_quirk(0, slot, func)) + break; + } }