Re: [PATCH v13 10/12] PCI: Assign unassigned bus resources in pci_scan_root_bus()

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Mon, 2014-09-29 at 12:06 -0700, Yinghai Lu wrote:
> On Mon, Sep 29, 2014 at 11:25 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> > On Mon, Sep 29, 2014 at 7:29 AM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
> >> If the firmware has not assigned all the bus resources and we are not just
> >> probing the PCI buses, it makes sense to assign the unassigned resources
> >> in pci_scan_root_bus().
> >>
> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> >> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> >> CC: Arnd Bergmann <arnd@arndb.de>
> >> CC: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
> >> CC: Rob Herring <robh+dt@kernel.org>
> >> ---
> >>  drivers/pci/probe.c | 3 +++
> >>  1 file changed, 3 insertions(+)
> >>
> >> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> >> index 636d1c9..d2ebd49 100644
> >> --- a/drivers/pci/probe.c
> >> +++ b/drivers/pci/probe.c
> >> @@ -1951,6 +1951,9 @@ 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;
> >>  }
> >
> > No, you can not do it that early.
> >
> > On x86, we need to call
> > pcibios_resource_survey_bus at first.
> 
> on x86:
> pcibios_init
> pcibios_resource_survey()
> pcibios_assign_resources() via fs_initcall
 
Right and on powerpc and others as well. We need to survey existing
resources. We also have a number of platform things that might need
to happen before we do the final re-assignment pass.

Ben.