From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754632AbYBQV43 (ORCPT ); Sun, 17 Feb 2008 16:56:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751499AbYBQV4U (ORCPT ); Sun, 17 Feb 2008 16:56:20 -0500 Received: from smtp02.lnh.mail.rcn.net ([207.172.157.102]:11174 "EHLO smtp02.lnh.mail.rcn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752525AbYBQV4T (ORCPT ); Sun, 17 Feb 2008 16:56:19 -0500 Date: Sun, 17 Feb 2008 16:56:17 -0500 (EST) Message-Id: <6gr00g$g7cm6f@smtp01.lnh.mail.rcn.net> From: "David P. Reed" To: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org Subject: [PATCH 0/3] x86: cleanup primary motherboard chip port access delays X-Junkmail-Status: score=10/50, host=mr02.lnh.mail.rcn.net X-Junkmail-SD-Raw: score=unknown, refid=str=0001.0A010204.47B8AD81.0093,ss=1,fgs=0, ip=207.172.4.11, so=2007-10-30 19:00:17, dmn=5.4.3/2007-11-16 X-Junkmail-IWF: false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org cleanup motherboard chip io port delays. inb_p and outb_p have traditionally used a write to port 80 (a non-existent port) as a delay. Though there is an argument that that is a good delay for devices on the ISA or PCI expansion buses it is not a good mechanism for devices in the processor chipset or on the "motherboard". The write to port 80 at best causes an abort on the ISA or LPC bus, and on some machines (like many of the HP laptops manufactured by Quanta) actually writes data to real i/o devices. For example, the ENE Embedded Controller chip family defaults to provide a register at port 80 that can be written, and which can cause an interrupt in the Embedded Controller. This has been shown to cause hangs on some machines, especially in accessing the CMOS RTC during bootup. This patch series addresses three of the places where these are used in common kernel code - in particular the three uses that affect the HP laptops mentioned above, modifying the delays to match the worst known delay issues for the specific chips. The patch set is complementary to the iodelay= kernel parameter added in 2.6.25, since it means fewer users will need to add that parameter to run linux "out of the box" without hanging. --