From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757050AbWK1Xuw (ORCPT ); Tue, 28 Nov 2006 18:50:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757085AbWK1Xuw (ORCPT ); Tue, 28 Nov 2006 18:50:52 -0500 Received: from einhorn.in-berlin.de ([192.109.42.8]:8083 "EHLO einhorn.in-berlin.de") by vger.kernel.org with ESMTP id S1757016AbWK1Xuv (ORCPT ); Tue, 28 Nov 2006 18:50:51 -0500 X-Envelope-From: stefanr@s5r6.in-berlin.de Message-ID: <456CCB53.70208@s5r6.in-berlin.de> Date: Wed, 29 Nov 2006 00:50:43 +0100 From: Stefan Richter User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.8) Gecko/20061113 SeaMonkey/1.0.6 MIME-Version: 1.0 To: Alan CC: linux1394-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [rfc PATCH] ieee1394: ohci1394: delete bogus spinlock, flush MMIO writes References: <20061128215621.2e0ac9a6@localhost.localdomain> In-Reply-To: <20061128215621.2e0ac9a6@localhost.localdomain> X-Enigmail-Version: 0.94.0.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Alan wrote: > On Tue, 28 Nov 2006 22:24:11 +0100 (CET) > Stefan Richter wrote: >> All MMIO writes which were surrounded by the spinlock as well as the >> very last MMIO write of the IRQ handler are now explicitly flushed by >> MMIO reads of the respective register. > > MMIO is ordered anyway on the bus, you just need mmiowb() to force > ordering to the bus controller in case you are on a big numa box. The mmiowb is a checkpoint to ensure ordering between different threads of MMIO writes; i.e. it doesn't halt the thread until the write actually reached the device like a read would do, right? -- Stefan Richter -=====-=-==- =-== ===-= http://arcgraph.de/sr/