From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 1/2]: serial8250: Use native_io_delay on the x86 Date: Wed, 17 Mar 2010 11:43:54 -0700 Message-ID: <4BA122EA.9030305@zytor.com> References: <20100317132849.7d49939b@marrow.netinsight.se> <20100317133050.54851ff8@marrow.netinsight.se> <4BA11EAA.20506@zytor.com> <20100317183608.600bcdf0@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: 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 In-Reply-To: <20100317183608.600bcdf0@lxorguk.ukuu.org.uk> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org 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 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