Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755748Ab3EFTDK (ORCPT ); Mon, 6 May 2013 15:03:10 -0400 Received: from terminus.zytor.com ([198.137.202.10]:45784 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755549Ab3EFTDI (ORCPT ); Mon, 6 May 2013 15:03:08 -0400 Message-ID: <5187FE55.8080601@zytor.com> Date: Mon, 06 May 2013 12:02:45 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: Bjorn Helgaas CC: Bin Gao , Thomas Gleixner , Ingo Molnar , "x86@kernel.org" , Jacob Pan , Jesse Barnes , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" Subject: Re: x86/pci/mrst: force all pci config toward 0:0:0, 0:2:0 and 0:3:0 to type 1 References: <20130430072147.GA37866@bingao-desk1.fm.intel.com> <20130502065358.GA41008@bingao-desk1.fm.intel.com> In-Reply-To: X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1701 Lines: 37 On 05/06/2013 10:38 AM, Bjorn Helgaas wrote: > On Wed, May 1, 2013 at 11:53 PM, Bin Gao wrote: >> On Wed, May 01, 2013 at 11:17:10AM -0600, Bjorn Helgaas wrote: >>> Is there any possibility of multi-function devices at bus 0, device 0, 2, or 3? >>> >>> What about bridges -- can any of these be a bridge? >>> >>> If either of those could happen, these checks could be too specific. >> 0:2:0 and 0:3:0 are the only 2 devices behind the bridge 0:0:0. > > Please use the conventional Linux PCI address formatting > (DDDD:BB:dd.f, where DDDD = domain (optional, often omitted if DDDD == > 0), BB = bus, dd = device, f = function), because this is quite > confusing. > > You say "0:2:0 and 0:3:0" are behind the bridge "0:0:0", but the patch > you sent clearly applies only to devices on bus 0. The patch applies > to devices 00:00.0, 00:02.0, and 00:03.0. These are all on the same > bus, so none of them can be behind a bridge. > > If the 00:00.0 device is in fact a bridge, its secondary bus will be > something other than 0, so any devices behind the bridge will be on a > non-zero bus number. And I assume you would want to use config > mechanism #1 to reach those devices, too. Your current patch doesn't > do that -- it only applies to devices on bus 0. > 0000:00:00.0 is presumably the *host bridge*, which is unique in PCI space in that it is a type 0 header and sits on what normally would be the client bus. -hpa -- 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/