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    SubjectRe: [PATCH 1/2] PCI: make pci_claim_resource() work with conflict resources as appropriate
    From
    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). So
    request_resource_conflict() for PCI quirks (0x1000-0x103f and 0x1100-0x110f)
    will simply return an error, coz these 2 regions 'conflict' with MSC PCI I/O.
    Instead, insert_resource_conflict() will also find the collisions but register
    quirks as children of MSC PCI I/O (is this supposed to be correct?) and return
    a success.


    Deng-Cheng

    2011/7/28 Ralf Baechle <ralf@linux-mips.org>
    >
    > On Thu, Jul 28, 2011 at 07:28:31PM +0800, Deng-Cheng Zhu wrote:
    >
    > > In resolving a network driver issue with the MIPS Malta platform, the root
    > > cause was traced into pci_claim_resource():
    > >
    > > MIPS System Controller's PCI I/O resources stay in 0x1000-0xffffff. When
    > > PCI quirks start claiming resources using request_resource_conflict(),
    > > collisions happen and -EBUSY is returned, thereby rendering the onboard AMD
    > > PCnet32 NIC unaware of quirks' region and preventing the NIC from functioning.
    > > For PCI quirks, PIIX4 ACPI is expected to claim 0x1000-0x103f, and PIIX4 SMB to
    > > claim 0x1100-0x110f, both of which fall into the MSC I/O range. Certainly, we
    > > can increase the start point of this range in arch/mips/mti-malta/malta-pci.c to
    > > avoid the collisions. But a fix in here looks more justified, though it seems to
    > > have a wider impact. Using insert_xxx as opposed to request_xxx will register
    > > PCI quirks' resources as children of MSC I/O and return OK, instead of seeing
    > > collisions which are actually resolvable.
    >
    > This used to work in the past; do you know which commit broke the resource
    > handling for the NIC?
    >
    >  Ralf
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