Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756032AbYAISMP (ORCPT ); Wed, 9 Jan 2008 13:12:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754134AbYAISL7 (ORCPT ); Wed, 9 Jan 2008 13:11:59 -0500 Received: from smtp-outbound-1.vmware.com ([65.113.40.141]:49399 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752092AbYAISL6 (ORCPT ); Wed, 9 Jan 2008 13:11:58 -0500 Subject: Re: [linux-kernel] Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override. From: Zachary Amsden To: Rene Herman Cc: Christer Weinigel , "David P. Reed" , Avi Kivity , Ondrej Zary , "H. Peter Anvin" , Bodo Eggert <7eggert@gmx.de>, Ingo Molnar , Alan Cox , Paul Rolland , Pavel Machek , Thomas Gleixner , linux-kernel@vger.kernel.org, Ingo Molnar , rol In-Reply-To: <4784E7E1.4060308@keyaccess.nl> References: <9BdU5-1YW-9@gated-at.bofh.it> <200801081810.58904.linux@rainbow-software.org> <4783B1B2.6070005@reed.com> <200801081838.16241.linux@rainbow-software.org> <4783C4A6.9060402@reed.com> <20080108185120.3ff7ed18@lxorguk.ukuu.org.uk> <4783CBD9.7020709@reed.com> <1199847162.7369.323.camel@bodhitayantram.eng.vmware.com> <20080109063052.48a5709c@weinigel.se> <4784E7E1.4060308@keyaccess.nl> Content-Type: text/plain Date: Wed, 09 Jan 2008 10:17:24 -0800 Message-Id: <1199902644.7369.355.camel@bodhitayantram.eng.vmware.com> Mime-Version: 1.0 X-Mailer: Evolution 2.10.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1645 Lines: 37 On Wed, 2008-01-09 at 16:27 +0100, Rene Herman wrote: > On 09-01-08 06:30, Christer Weinigel wrote: > I'd not expect very time crtical. The current outb_p use gives a delay > somewhere between .5 and 2 microseconds as per earlier survey meaning a > udelay(1) or 2 would be enough -- again, at the point that udelay() is sensible. > > New machines don't use the legacy PIC anymore anyway. > > > The floppy controller code uses outb_p. Even though there might be > > floppy controllers on modern systems, I'd rather leave the floppy code > > alone since it's supposed to be very fragile. If you still use > > floppies you deserve what you get. > > Floppies forever. In practice, leaving it alone isn't going to matter, but > in that same practice changing it to udelay() probably doesn't either. The > ones to leave alone are the ones that are clumsy/impossible to test and the > ones such as in NIC drivers that were specifically tuned. I'm speaking specifically in terms of 64-bit platforms here. Shouldn't we unconditionally drop outb_p doing extra port I/O on 64-bit architectures? Especially considering they don't even have an ISA bus where the decode timing could even matter? > If simple outb_p() deprecation is considered enough instead, no need to > touch anything in drivers/, only changes to "outb(); udelay()" outside drivers/. > > I'd let Alan decide here. Agree. Zach -- 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/