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 11:25:46 -0700 Message-ID: <4BA11EAA.20506@zytor.com> References: <20100317132849.7d49939b@marrow.netinsight.se> <20100317133050.54851ff8@marrow.netinsight.se> 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]:52248 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754584Ab0CQS0s (ORCPT ); Wed, 17 Mar 2010 14:26:48 -0400 In-Reply-To: <20100317133050.54851ff8@marrow.netinsight.se> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Simon Kagstrom Cc: 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 05:30 AM, Simon Kagstrom wrote: > #ifdef __i386__ > - outb(0xff, 0x080); > + native_io_delay(); > #endif There is something a lot more weird about this. First of all, it's #ifdef'd out on all but __i386__ including x86-64; second, it looks like this is specific to synchronizing to the IER. I'm wondering if the right thing isn't to add a dummy write to the SCR register (or similar.) -hpa