From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:46989 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756224Ab2DKPem (ORCPT ); Wed, 11 Apr 2012 11:34:42 -0400 Received: by pbcun15 with SMTP id un15so1362119pbc.19 for ; Wed, 11 Apr 2012 08:34:41 -0700 (PDT) Message-ID: <4F85A481.1020807@gmail.com> Date: Wed, 11 Apr 2012 23:34:25 +0800 From: Jiang Liu MIME-Version: 1.0 To: Kenji Kaneshige CC: Bjorn Helgaas , Yinghai Lu , Taku Izumi , Jiang Liu , Keping Chen , linux-pci@vger.kernel.org Subject: Re: [PATCH V4 0/6] PCI, x86: update MMCFG information when hot-plugging PCI host bridges References: <1334103063-2283-1-git-send-email-jiang.liu@huawei.com> <4F8573A4.8070307@jp.fujitsu.com> In-Reply-To: <4F8573A4.8070307@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-pci-owner@vger.kernel.org List-ID: On 04/11/2012 08:05 PM, Kenji Kaneshige wrote: > (2012/04/11 13:02), Bjorn Helgaas wrote: >> On Tue, Apr 10, 2012 at 6:10 PM, Jiang Liu wrote: >>> This patchset enhance pci_root driver to update MMCFG information when >>> hot-plugging PCI root bridges. It applies to Yinghai's tree at >>> git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-pci-root-bus-hotplug >>> >>> The second patch is based on Taku Izumi work with some enhancements to >>> correctly handle PCI host bridges without _CBA method. >> >> I'm sorry I won't have time to really review these for a couple weeks. >> >> It always seemed wrong to me that we parse MCFG and set things up >> before we even look at PNP0A03/PNP0A08 devices. It would make more >> sense to me to have something in acpi_pci_root_add() to set up >> MMCONFIG using _CBA if available, and falling back to parsing MCFG if >> it's not. > > I think your idea could make the code (design) much cleaner. > Do you have any other reason why you think "It always seemed > wrong..."? Yeah, that may lead to a cleaner design. But there are still some special cases, such as: 1) ACPI subsystem is disabled by kernel boot options, so we can't rely on the ACPI pci_root driver to initialize the MMCFG. 2) Some PCI host bridges are not reported by the ACPI namespace. My partner has observed a system which doesn't report the host bridges embedded in the NHM-EX processors. Thanks! > > Regards, > Kenji Kaneshige