Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755507Ab3EFS5A (ORCPT ); Mon, 6 May 2013 14:57:00 -0400 Received: from mail-ob0-f173.google.com ([209.85.214.173]:59091 "EHLO mail-ob0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755205Ab3EFS47 (ORCPT ); Mon, 6 May 2013 14:56:59 -0400 MIME-Version: 1.0 In-Reply-To: References: <20130430072147.GA37866@bingao-desk1.fm.intel.com> <20130502065358.GA41008@bingao-desk1.fm.intel.com> From: Bjorn Helgaas Date: Mon, 6 May 2013 11:56:38 -0700 Message-ID: Subject: Re: x86/pci/mrst: force all pci config toward 0:0:0, 0:2:0 and 0:3:0 to type 1 To: Bin Gao Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "x86@kernel.org" , Jacob Pan , Jesse Barnes , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2797 Lines: 63 On Mon, May 6, 2013 at 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? I hate it when I go to the trouble of reviewing something and asking relevant questions, and then people ignore the questions :( I'd still like to know whether multi-function devices are possible at bus 0, device 0, 2, or 3. Are these devices built-in, so you know exactly what they are and they can never be anything else? Or is there a slot or other way to connect a user-chosen device? >>> 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. If you included "lspci -vv" output, that would make this much easier to talk about. > 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. > > I dropped this patch until this gets straightened out. > >> These devices don't implement pcie capability list in legacy config space >> so no offset above 255 would be triggered. >> The fixed bar pcie capability located at 0x100 is for pci-shimed device >> only, not for 0, 2 and 3. But current implementation applies it to 0, >> 2 and 3 as well. This is what the patch is going to address. >> >>> >>> Is there a doc that identifies these cases where config mechanism #1 >>> should be used instead of MMCONFIG? >> Unfortunately no doc identifies this. >> But since FW doesn't provide pci shim for device 0, 2 and 3, >> and these 3 real pci devices have only 256 bytes legacy pci >> config space so they can only be accessed by type 1. >> >>> >>> Bjorn >>> -- 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/