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    SubjectRe: [PATCH v2 06/29] x86/PCI: convert to pci_create_root_bus() and pci_scan_root_bus()
    On 10/14/2011 01:54 PM, Bjorn Helgaas wrote:

    > On Fri, Oct 14, 2011 at 2:39 PM, Yinghai Lu <yinghai.lu@oracle.com> wrote:
    >> On 10/14/2011 01:32 PM, Bjorn Helgaas wrote:
    >>
    >>
    >>>>> int node;
    >>>>> @@ -353,11 +349,18 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
    >>>>> memcpy(bus->sysdata, sd, sizeof(*sd));
    >>>>> kfree(sd);
    >>>>> } else {
    >>>>> - bus = pci_create_bus(NULL, busnum, &pci_root_ops, sd);
    >>>>> - if (bus) {
    >>>>> - get_current_resources(device, busnum, domain, bus);
    >>>>> - bus->subordinate = pci_scan_child_bus(bus);
    >>>>> + INIT_LIST_HEAD(&resources);
    >>>>> + get_current_resources(device, busnum, domain, &resources);
    >>>>> + if (!pci_use_crs) {
    >>>>> + pci_free_resource_list(&resources);
    >>>>> + x86_pci_root_bus_resources(busnum, &resources);
    >>>>> }
    >>>>
    >>>>
    >>>> You may need to update get_current_resources() to return status about handling _CRS...
    >>>> and check that status insteaf of !pci_use_crs.
    >>>
    >>> Is the current patch broken here? I don't think it will be simpler to
    >>> have get_current_resources() return a status and check that. But if
    >>> something's actually broken, I want to fix it, of course.
    >>>
    >>
    >>
    >> yes. if for some reason, _CRS is not handled right, that root bus resources will not get set to default res.
    >>
    >> + status = get_current_resources(device, busnum, domain, &resources);
    >> + if (status) {
    >> + pci_free_resource_list(&resources);
    >> + x86_pci_root_bus_resources(busnum, &resources);
    >> }
    >>
    >> get_current_resources() will not return 0 if _CRS is not really used.
    >
    > OK. I think it was that way before, too. We created the bus with
    > default resources, but the first thing get_current_resources() did was
    > clear them all out. If there was a problem parsing _CRS, we never
    > went back and put the defaults back in.


    that means you broke it when you clean up it last time.

    >
    > But I think this will do what you suggest and is nicer than what I had before:
    >
    > INIT_LIST_HEAD(&resources);
    > get_current_resources(device, busnum, domain, &resources);
    > if (list_empty(&resources))
    > x86_pci_root_bus_resources(busnum, &resources);


    yes, that should work.

    Yinghai


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