From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755431Ab0CQSot (ORCPT ); Wed, 17 Mar 2010 14:44:49 -0400 Received: from terminus.zytor.com ([198.137.202.10]:41731 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754132Ab0CQSos (ORCPT ); Wed, 17 Mar 2010 14:44:48 -0400 Message-ID: <4BA122EA.9030305@zytor.com> Date: Wed, 17 Mar 2010 11:43:54 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.8) Gecko/20100301 Fedora/3.0.3-1.fc12 Thunderbird/3.0.3 MIME-Version: 1.0 To: Alan Cox CC: Simon Kagstrom , x86@kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, alan@linux.intel.com, akpm@linux-foundation.org Subject: Re: [PATCH 1/2]: serial8250: Use native_io_delay on the x86 References: <20100317132849.7d49939b@marrow.netinsight.se> <20100317133050.54851ff8@marrow.netinsight.se> <4BA11EAA.20506@zytor.com> <20100317183608.600bcdf0@lxorguk.ukuu.org.uk> In-Reply-To: <20100317183608.600bcdf0@lxorguk.ukuu.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/17/2010 11:36 AM, Alan Cox wrote: > > You just need a write to something on the ISA bus which is 'safe' so that > you don't end up reading back what you wrote to an non-existant port as > some old chipsets will return the last ISA result when you do this rather > than 0xff. Ah... floating bus syndrome. So how about writing 0xff to the SCR register in the same register range? -hpa