On Wed, Aug 24, 2011 at 12:24 AM, Deng-Cheng Zhu
<dengcheng.zhu@xxxxxxxxx> wrote:
> Currently, after pci_create_bus(), resources available on the bus could be
> handled by pci_scan_child_bus(). The problem is that, in
> pci_scan_child_bus(), before calling arch-dependent pcibios_fixup_bus(),
> PCI quirks will probably conflict (while doing pci_claim_resource()) with
> resources like system controller's I/O resource that have not yet been
> added to the bus. So, add those resources right before returning the newly
> created bus in pci_create_bus().
I like this approach a lot. Thanks for working it up. It's a nice
small change with very little impact to other architectures, and you
have a nice clear changelog. You might mention something about the
fact that by default, the bus starts out with all of ioport_resource
and iomem_resource -- that will mean something to people who know how
host bridges work.
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 8473727..7735fe7 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1516,7 +1516,8 @@ unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus)
> }
>
> struct pci_bus * pci_create_bus(struct device *parent,
> - int bus, struct pci_ops *ops, void *sysdata)
> + int bus, struct pci_ops *ops, void *sysdata,
> + struct pci_bus_resource *bus_res)
> {
> int error;
> struct pci_bus *b, *b2;
> @@ -1570,8 +1571,14 @@ struct pci_bus * pci_create_bus(struct device *parent,
> pci_create_legacy_files(b);
>
> b->number = b->secondary = bus;
> - b->resource[0] = &ioport_resource;
> - b->resource[1] = &iomem_resource;
> +
> + /* Add initial resources to the bus */
> + if (bus_res != NULL) {
> + list_add_tail(&b->resources, &bus_res->list);
> + } else {
> + pci_bus_add_resource(b, &ioport_resource, 0);
> + pci_bus_add_resource(b, &iomem_resource, 0);
> + }
Using pci_bus_add_resource() here *seems* like it should be the right
thing, but I don't think it will work correctly.
The problem is that struct pci_bus has both a table of resources
(bus->resource[]) *and* a list (bus->resources).
pci_bus_add_resource() always puts the new resource on the list, but
various arch code still references the table directly, e.g., sparc has
"pbus->resource[0] = &pbm->io_space" in pcibios_fixup_bus().
As written, I think this patch will break sparc because the host
bridge will end up with both pbm->io_space (in the table) and
ioport_resource (in the list).
I think something like this would work, though:
if (bus_res)
list_add_tail(&b->resources, &bus_res->list);
else {
b->resource[0] = &ioport_resource;
b->resource[1] = &iomem_resource;
}
Bjorn
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