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. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/