From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751949AbWJXTWN (ORCPT ); Tue, 24 Oct 2006 15:22:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751942AbWJXTWN (ORCPT ); Tue, 24 Oct 2006 15:22:13 -0400 Received: from havoc.gtf.org ([69.61.125.42]:7634 "EHLO havoc.gtf.org") by vger.kernel.org with ESMTP id S1751798AbWJXTWM (ORCPT ); Tue, 24 Oct 2006 15:22:12 -0400 Date: Tue, 24 Oct 2006 15:22:10 -0400 From: Jeff Garzik To: Roland Dreier Cc: linux-pci@atrey.karlin.mff.cuni.cz, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, openib-general@openib.org, John Partridge Subject: Re: Ordering between PCI config space writes and MMIO reads? Message-ID: <20061024192210.GE2043@havoc.gtf.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 24, 2006 at 12:13:19PM -0700, Roland Dreier wrote: > 1) Is this something that should be fixed in the driver? The PCI > spec allows MMIO cycles to start before an earlier config cycle > completed, but do we want to expose this fact to drivers? Would > it be better for ia64 to use some sort of barrier to make sure > pci_write_config_xxx() is strongly ordered with MMIO? The PCI config APIs have traditionally enforced very strong ordering. Heck, the PCI config APIs often take a spinlock on each read or write; so they are definitely not intended to be as fast as MMIO. Jeff