On Fri, Feb 24, 2012 at 2:24 PM, Jesse Barnes [off-list ref] wr=
ote:

On Thu, 23 Feb 2012 12:51:30 -0800
Bjorn Helgaas [off-list ref] wrote:

quoted

2) We already have a way to add resources to a root bus: the
pci_add_resource() used to add I/O port and MMIO apertures. =A0I think
it'd be a lot simpler to just use that same interface for the bus
number aperture, e.g.,

=A0 =A0 pci_add_resource(&resources, hose->io_space);
=A0 =A0 pci_add_resource(&resources, hose->mem_space);
=A0 =A0 pci_add_resource(&resources, hose->busnr_space);
=A0 =A0 bus =3D pci_scan_root_bus(dev, next_busno, pci_ops, sysdata, &re=

sources);

quoted

This is actually a bit redundant, since "next_busno" should be the
same as hose->busnr_space->start. =A0So if we adopted this approach, we
might want to eventually drop the "next_busno" argument.

Yeah that would be nice, the call would certainly make more sense that
way.

no, I don't think so.

using pci_add_resource will need to create dummy resource abut bus range.

there is lots of pci_scan_root_bus(),  and those user does not bus end
yet before scan.
so could just hide pci_insert_busn_res in pci_scan_root_bus, and
update busn_res end there.

other arch like x86, ia64, powerpc, sparc, will insert exact bus range
between pci_create_root_bus and
pci_scan_child_bus, will not need to update busn_res end.

please check v7 of this patchset.

    	git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.gi=
t
for-pci-busn-alloc

It should be clean and have minimum lines of change.

Thanks

      Yinghai