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    SubjectRe: [PATCH 1/2] PCI: make pci_claim_resource() work with conflict resources as appropriate
    On Fri, Jul 29, 2011 at 12:32 AM, Deng-Cheng Zhu
    <dengcheng.zhu@gmail.com> wrote:
    > I noticed that at 79896cf42f Linus changed the function from insert_resource()
    > to request_resource() (and later evolved into request_resource_conflict()) and
    > he explained the reason. So, in the NIC's case, the problem is that in
    > pci_claim_resource() the function pci_find_parent_resource() returns the root
    > (0x0-0xffffff) rather than the MSC PCI I/O (0x1000-0xffffff).

    This seems like the real problem: PCI has the wrong idea of the
    resources available on bus 00. The pci_bus->resource[0] for bus 00
    points to ioport_resource (the default put there by pci_create_bus()),
    when it should point to to msc_io_resource instead.

    Some architectures fill in the pci_bus->resource[] array directly for
    host bridges (for examples, try 'grep -r "resource\[0\] = " arch/').
    On x86 and ia64, we use pci_bus_remove_resources() and
    pci_bus_add_resource(), and I'd prefer that style for new code because
    it hides some ugly implementation details.

    I'm a little puzzled that we don't see this problem on more
    architectures. The grep above only found a few arches that update the
    root bus resources. I would expect most of the ones it didn't find to
    be broken the same way Malta is.

    Bjorn


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