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    SubjectRe: [PATCH v10 09/10] PCI: Assign unassigned bus resources in pci_scan_root_bus()
    On 9/8/2014 8:54 AM, Liviu Dudau wrote:
    > If the firmware has not assigned all the bus resources and
    > we are not just probing the PCIe busses, it makes sense to
    > assign the unassigned resources in pci_scan_root_bus().
    >
    > Cc: Bjorn Helgaas <bhelgaas@google.com>
    > Cc: Arnd Bergmann <arnd@arndb.de>
    > Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
    > Cc: Rob Herring <robh+dt@kernel.org>
    > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
    > ---
    > drivers/pci/probe.c | 3 +++
    > 1 file changed, 3 insertions(+)
    >
    > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
    > index ef891d2..508cf61 100644
    > --- a/drivers/pci/probe.c
    > +++ b/drivers/pci/probe.c
    > @@ -1953,6 +1953,9 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
    > if (!found)
    > pci_bus_update_busn_res_end(b, max);
    >
    > + if (!pci_has_flag(PCI_PROBE_ONLY))
    > + pci_assign_unassigned_bus_resources(b);
    > +
    > pci_bus_add_devices(b);
    > return b;
    > }
    >

    Liviu,

    Besides the check for PCI_PROBE_ONLY here, I think we also need to avoid calling
    "pci_enable_resources()" in the "driver/pci/pci.c: pcibios_enable_device()" for
    PCI_PROBE_ONLY mode since the resource is not assigned by Linux. Otherwise, the
    "drivers/pci/setup-res.c: pci_enable_resource()" would fail w/ error:

    can't enable device: BAR ..... not assigned

    Actually, in "arch/arm/kernel/bios32.c:", the weak "pcibios_enable_device()" function
    also has the check for PCI_PROBE_ONLY mode before calling pci_enable_resources().

    Thanks,

    Suravee



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