Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757397AbYAHNSP (ORCPT ); Tue, 8 Jan 2008 08:18:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753346AbYAHNR7 (ORCPT ); Tue, 8 Jan 2008 08:17:59 -0500 Received: from moutng.kundenserver.de ([212.227.126.183]:49215 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751163AbYAHNR6 (ORCPT ); Tue, 8 Jan 2008 08:17:58 -0500 Date: Tue, 8 Jan 2008 14:17:49 +0100 (CET) From: Bodo Eggert <7eggert@gmx.de> To: Alan Cox cc: Bodo Eggert <7eggert@gmx.de>, "H. Peter Anvin" , Christer Weinigel , Ingo Molnar , "David P. Reed" , Rene Herman , Paul Rolland , Pavel Machek , Thomas Gleixner , linux-kernel@vger.kernel.org, Ingo Molnar , rol@witbe.net Subject: Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override. In-Reply-To: <20080107232514.699155d6@lxorguk.ukuu.org.uk> Message-ID: References: <9BdU5-1YW-9@gated-at.bofh.it> <9BeZN-3Gf-5@gated-at.bofh.it> <9BnTB-1As-31@gated-at.bofh.it> <9BrX4-8go-1@gated-at.bofh.it> <9BuBG-4eR-51@gated-at.bofh.it> <9BvRd-6aL-71@gated-at.bofh.it> <9GRQW-1DX-13@gated-at.bofh.it> <9GSah-23W-1@gated-at.bofh.it> <9GSDy-2GD-23@gated-at.bofh.it> <9GTpK-40d-15@gated-at.bofh.it> <9GUvy-5H2-11@gated-at.bofh.it> <9GVKU-7SS-25@gated-at.bofh.it> <478281A6.1000704@zytor.com> <20080107232514.699155d6@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii X-be10.7eggert.dyndns.org-MailScanner-Information: See www.mailscanner.info for information X-be10.7eggert.dyndns.org-MailScanner: Found to be clean X-be10.7eggert.dyndns.org-MailScanner-From: 7eggert@gmx.de X-Provags-ID: V01U2FsdGVkX1/F862S0zteZHn0rrli9QMTWW4e+SRy2KmvBN1 UETEXuZVcdUsDnU7w8hzBqeHhIoBk3aPxDpolhAZHbyG9h23qb KxOxP6xOJcXIIira5mSGQ== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1262 Lines: 28 On Mon, 7 Jan 2008, Alan Cox wrote: > > But overclocking is not the problem for udelay, it would err to the safe > > side. The problem would be a BUS having < 8 MHz, and since the days of > > 80286, they are hard to find. IMO having an option to set the bus speed > > for those systems should be enough. > > If you get it wrong you risk data corruption. Not good, not clever, not > appropriate. Basically the use of port 0x80 is the right thing to do for > ISA devices and as 15 odd years of use has shown works reliably and > solidly for ISA systems. As long as there is no port 80 card or a similar device using it. If there is a port 80 card, ISA acess needing the delay does break, cause the data corruption you fear and does cause this thread to be started. Pest, Cholera ... OTOH, maybe the 6-MHz-delay is the same as the 8-MHz-delay, and the kernel parameter is not needed. -- Fun things to slip into your budget A Romulan Cloaking device: The PHB won't know what it is but will be to chicken to ask -- 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/