From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp07.in.ibm.com ([122.248.162.7]:48565 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932839Ab2EPBSl (ORCPT ); Tue, 15 May 2012 21:18:41 -0400 Received: from /spool/local by e28smtp07.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 16 May 2012 06:48:38 +0530 Date: Wed, 16 May 2012 09:18:34 +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: <20120516011833.GA6599@richard> Reply-To: Richard Yang References: <20120410090306.GA7056@richard> <20120422155202.GA13540@richard> <4F95B17B.3030401@redhat.com> <20120514015536.GA3331@richard> <20120514064615.GB26605@richard> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: Sender: linux-pci-owner@vger.kernel.org List-ID: On Tue, May 15, 2012 at 10:32:46AM -0700, Yinghai Lu wrote: >On Sun, May 13, 2012 at 11:46 PM, Richard Yang > wrote: >> 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. >>>>>> >>>> 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. > >with that new condition, probe_resource will return zero. > >for those kind of case: >1. use echo 1 > /sys .../remove to remove devices under Bridge2. >2. use setpci to change bus register of bridge2 to move high to make >more space for bridge 1. >3. rescan bridge 1 and bridge 2. So these steps is done after boot up and user find B3 doesn't work? > >Yinghai -- Richard Yang Help you, Help me