Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754353Ab2ENGqY (ORCPT ); Mon, 14 May 2012 02:46:24 -0400 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:48757 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753263Ab2ENGqX (ORCPT ); Mon, 14 May 2012 02:46:23 -0400 Date: Mon, 14 May 2012 14:46:15 +0800 From: Richard Yang To: Yinghai Lu Cc: Richard Yang , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: One problem in reassign pci bus number? Message-ID: <20120514064615.GB26605@richard> Reply-To: Richard Yang References: <20120410090306.GA7056@richard> <20120422155202.GA13540@richard> <4F95B17B.3030401@redhat.com> <20120514015536.GA3331@richard> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) x-cbid: 12051406-8878-0000-0000-000002713600 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2615 Lines: 71 On Sun, May 13, 2012 at 10:40:41PM -0700, Yinghai Lu wrote: >On Sun, May 13, 2012 at 6:55 PM, Richard Yang > wrote: >> On Mon, Apr 23, 2012 at 03:46:03PM -0400, Don Dutile wrote: >>>On 04/22/2012 11:52 AM, Richard Yang wrote: >>>>All, >>>> >>>>I am reading the pci_scan_bridge() and not sure what will happen in >>>>following situation. >>>> >>>>Suppose the kernel is not passed the pci=assign-busses. >>>> >>>>Below is a picture about the pci system. >>>> >>>> ? ? ? ? ? ? ? ? ? ?+-------+ >>>> ? ? ? ? ? ? ? ? ? ?| ? ? ? | root bridge(0,255) >>>> ? ? ? ? ? ? ? ? ? ?+---+---+ >>>> ? ? ? ? ? ? ? ? ? ? ? ?| ? ? ? ? ?Bus 0 >>>> ? ? ? -----+-----------+------------------------------+-- >>>> ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| >>>> ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| >>>> ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| >>>> ? ? ? +----+----+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? +-----+-----+ >>>> ? ? ? | ? ? ? ? | ?B1(1,15) ? ? ? ? ? ? ? ? ? ? | ? ? ? ? ? |B2(16,28) >>>> ? ? ? +----+----+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? +-----+-----+ >>>> ? ? ? ? ? ?| ?Bus 1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?Bus 16 >>>> ? ? ? -----+----------------------- ? ? ? ? ----------+---------------- >>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? | >>>> ? ? ? ? ? ? ? ? ? ? ? ?+----+----+ >>>> ? ? ? ? ? ? ? ? ? ? ? ?| ? ? ? ? | B3 >>>> ? ? ? ? ? ? ? ? ? ? ? ?+---------+ >>>> >>>>Suppose B1 and B2 works fine with the BIOS, which get the right bus >>>>number and range. >>>> >>>>B3 does not works fine with the BIOS, which doesn't get the bus number. >>>> >>>>So in pci_scan_bridge(), B3 will be met in the second pass and get bus >>>>number 16? >>> >> Yinghai, >> >> Take my original question. >> >> B3 doesn't get the bus number, which its parent doesn't have free bus >> number and there is no gap between B1 and B2. >> >> So in this case, the probe_resource() can't find bus number for B3. >> Then cause pci_bridge_probe_busn_res() return non-zero. >> >> Then B3 couldn't work fine? > >B3 is on Bus 1? B3 is the one of bridges on Bus1? No, I omit other bridges on Bus#1. They will occupy bus number 2-15, which is calculated by BIOS and set to bridge's configuration space. > >if B3 is only bridge on Bus1, it probe_resource should return [2,15] >at first, and then scan B3. > >Yinghai -- Richard Yang Help you, Help me -- 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/