It was found that PCI quirks claim resources (by calling pci_claim_resource()) *BEFORE* pcibios_fixup_bus() is called. In pcibios_fixup_bus(), pci_bus->resource[0] for the root bus DOES point to msc_io_resource. If PCI quirks do the resource claim after the arch-defined pcibios_fixup_bus() being called, then the problem with Malta goes away. So, it looks like 2 solutions out there: 1) To manage the call sequence. This seems not a desired one as it affects other arches. 2) To raise the start point of the system controller's io_resource in mips_pcibios_init() in arch/mips/mti-malta/malta-pci.c. This will place PCI quirks' resources at the same level of the system controller's resources. Ralf and Bjorn, which one sounds good to you? Deng-Cheng 2011/7/30 Bjorn Helgaas <bhelgaas@xxxxxxxxxx>: > On Fri, Jul 29, 2011 at 12:32 AM, Deng-Cheng Zhu > <dengcheng.zhu@xxxxxxxxx> 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 >
