From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756058AbaKROYG (ORCPT ); Tue, 18 Nov 2014 09:24:06 -0500 Received: from service87.mimecast.com ([91.220.42.44]:38217 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754556AbaKROYA convert rfc822-to-8bit (ORCPT ); Tue, 18 Nov 2014 09:24:00 -0500 Date: Tue, 18 Nov 2014 14:23:54 +0000 From: Liviu Dudau To: Yijing Wang Cc: Arnd Bergmann , "linux-arm-kernel@lists.infradead.org" , Liviu Dudau , Tony Luck , Russell King , "linux-pci@vger.kernel.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "huxinwei@huawei.com" , Thierry Reding , "suravee.suthikulpanit@amd.com" , Benjamin Herrenschmidt , Bjorn Helgaas , "linux-ia64@vger.kernel.org" , Thomas Gleixner , Wuyun , "linuxppc-dev@lists.ozlabs.org" , Yijing Wang Subject: Re: [RFC PATCH 01/16] PCI: Enhance pci_scan_root_bus() to support default IO/MEM resources Message-ID: <20141118142354.GH12037@e106497-lin.cambridge.arm.com> References: <1416219710-26088-1-git-send-email-wangyijing@huawei.com> <2732970.7HG94QvVBv@wuerfel> <546AF8D7.9010103@huawei.com> <2447172.ADYWdCTnMP@wuerfel> <546B317E.4090800@huawei.com> MIME-Version: 1.0 In-Reply-To: <546B317E.4090800@huawei.com> User-Agent: Mutt/1.5.22 (2013-10-16) X-OriginalArrivalTime: 18 Nov 2014 14:23:56.0098 (UTC) FILETIME=[49455A20:01D0033B] X-MC-Unique: 114111814235800201 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 18, 2014 at 11:46:06AM +0000, Yijing Wang wrote: > On 2014/11/18 17:36, Arnd Bergmann wrote: > > On Tuesday 18 November 2014 15:44:23 Yijing Wang wrote: > >> On 2014/11/17 18:08, Arnd Bergmann wrote: > >>> On Monday 17 November 2014 18:21:35 Yijing Wang wrote: > >>>> - list_for_each_entry(window, resources, list) > >>>> - if (window->res->flags & IORESOURCE_BUS) { > >>>> - found = true; > >>>> - break; > >>>> - } > >>>> + if (!resources) { > >>>> + pci_add_resource(&default_res, &ioport_resource); > >>>> + pci_add_resource(&default_res, &iomem_resource); > >>>> + pci_add_resource(&default_res, &busn_resource); > >>>> + } else { > >>>> > >>> > >>> Isn't it almost always wrong to do this? You are adding all of the > >>> I/O ports and memory to the host bridge, which will prevent you from > >>> adding another host bridge, and the iomem_resource normally > >>> includes a lot of addresses that are not accessible by the PCI host. > >> > >> Hi Arnd, pci host bridge windows are the ranges allow child devices to setup > >> from. Add all of IO/MEM here just a limit to child devices, no request for these > >> resources, so it won't hurt another host bridge. Some platforms have no dts or ACPI > >> report host bridge resources, in this case, we directly assign ioport/iomem_resources > >> as the root resources of PCI devices. > > > > But it would be wrong to allow hosts to allocate a device BAR that is not > > visible through the host bridge. I think we need to keep these separate > > from the general case: if you call any of the modern interfaces you have > > to provide the resources and a device. I notice that there is only one > > caller of pci_scan_bus_parented(), we should probably change that over to > > pci_scan_root_bus() or your new interface and remove the old one, but > > keep pci_scan_bus() as the only entry point for all of the legacy users > > that do not know about the resources. > > Ok, I will move this out of the generic interface. My suggestion would actually be to trigger a warning/error if you detect that the resources are missing. That way we can force the drivers to clean up. Best regards, Liviu > > Thanks! > Yijing. > > > > > Arnd > > > > . > > > > > -- > Thanks! > Yijing > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯