Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992690AbWKAROq (ORCPT ); Wed, 1 Nov 2006 12:14:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992691AbWKAROq (ORCPT ); Wed, 1 Nov 2006 12:14:46 -0500 Received: from palinux.external.hp.com ([192.25.206.14]:38595 "EHLO mail.parisc-linux.org") by vger.kernel.org with ESMTP id S2992690AbWKAROp (ORCPT ); Wed, 1 Nov 2006 12:14:45 -0500 Date: Wed, 1 Nov 2006 10:14:44 -0700 From: Matthew Wilcox To: John Partridge Cc: Roland Dreier , "Richard B. Johnson" , "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, jeff@garzik.org, openib-general@openib.org, linux-pci@atrey.karlin.mff.cuni.cz, David Miller Subject: Re: Ordering between PCI config space writes and MMIO reads? Message-ID: <20061101171443.GI11399@parisc-linux.org> References: <20061024.154347.77057163.davem@davemloft.net> <20061031195312.GD5950@mellanox.co.il> <019301c6fd2c$044d7010$0732700a@djlaptop> <20061031204717.GG26964@parisc-linux.org> <4548CAE7.8010300@sgi.com> <20061101164643.GH11399@parisc-linux.org> <4548D478.2080704@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4548D478.2080704@sgi.com> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 986 Lines: 19 On Wed, Nov 01, 2006 at 11:08:08AM -0600, John Partridge wrote: > So, if I understand correctly, you are saying because we cannot guarantee > the "flush" a config write even by doing a config read of the same register > (because the PPB can re-order) we have to make sure we block or spin on the > config write completion at the lowest level of the config write ? That's correct. And I'm also saying that the reason this hasn't been thought about before is that other root bridges have a mechanism (implicit on x86, explicit on parisc) for waiting for the config write completion to come back. Seems to me that Altix uses the SAL calls to access PCI config space these days, so you can hide it in your firmware rather than patching Linux. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/