Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758423AbXL3VWx (ORCPT ); Sun, 30 Dec 2007 16:22:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755032AbXL3VWq (ORCPT ); Sun, 30 Dec 2007 16:22:46 -0500 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:39050 "EHLO the-village.bc.nu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1755004AbXL3VWp (ORCPT ); Sun, 30 Dec 2007 16:22:45 -0500 Date: Sun, 30 Dec 2007 21:13:29 +0000 From: Alan Cox To: Linus Torvalds Cc: Rene Herman , Ingo Molnar , dpreed@reed.com, Islam Amer , hpa@zytor.com, Pavel Machek , Ingo Molnar , Andi Kleen , Thomas Gleixner , Linux Kernel Subject: Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override Message-ID: <20071230211329.39ae77c2@the-village.bc.nu> In-Reply-To: References: <477711DC.5030800@keyaccess.nl> <20071230144700.78f4605c@the-village.bc.nu> <20071230152835.GX16946@elte.hu> <4777BDA5.4050203@keyaccess.nl> X-Mailer: Claws Mail 3.1.0 (GTK+ 2.10.14; i386-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1119 Lines: 24 > But that does't mean that other ports won't have the same timings. Also, > it doesn't mean that we really need to have exactly *those* timings. For ISA bus you want "at least" those timings. That is an easy case anyway - ISA bus boxes, old processors and generally no TSC so we can fall back to 0x80 - we know from 15 years experience the problem only occurs with recent non ISA systems that have borked firmware. Lots of ISA hardware does really need the delays and most of it will be on old processors as well naturally enough. > I also think that the worries about PCI write posting are unnecessary. IO > port accesses (ie a regular "inb()" and "outb()" even _without_ the "_p()" > format slowdown) are already synchronous not only by the CPU but by all Ok then the SCSI examples should be fine (although as I said I think they are possibly bogus anyway) Alan -- 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/