On Wed, Jun 26, 2013 at 05:37:58PM -0600, Bjorn Helgaas wrote:
> On Tue, Jun 25, 2013 at 10:22 AM, Mika Westerberg
> <mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> > From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> >
> > pci_scan_slot() returns number of new devices connected *directly*
> > connected to the slot. Current enable_device() checks the return value
> > and stops if it doesn't see a new device.
> >
> > In Thunderbolt chaining case the new device can be deeper in hierarchy, so
> > do the rescan anyway.
> >
> > Because of that we must make sure that pcibios_resource_survey_bus() and
> > check_hotplug_bridge() get called only for a just found bus and not the
> > ones already added to the system. Failure to do so will lead to resource
> > conflicts.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > ---
> > drivers/pci/hotplug/acpiphp_glue.c | 18 +++++++-----------
> > 1 file changed, 7 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> > index b983e29..80a6ea1 100644
> > --- a/drivers/pci/hotplug/acpiphp_glue.c
> > +++ b/drivers/pci/hotplug/acpiphp_glue.c
> > @@ -685,18 +685,13 @@ static int __ref enable_device(struct acpiphp_slot *slot)
> > struct pci_dev *dev;
> > struct pci_bus *bus = slot->bridge->pci_bus;
> > struct acpiphp_func *func;
> > - int num, max, pass;
> > + int max, pass;
> > LIST_HEAD(add_list);
> >
> > list_for_each_entry(func, &slot->funcs, sibling)
> > acpiphp_bus_add(func);
> >
> > - num = pci_scan_slot(bus, PCI_DEVFN(slot->device, 0));
> > - if (num == 0) {
> > - /* Maybe only part of funcs are added. */
> > - dbg("No new device found\n");
> > - goto err_exit;
> > - }
> > + pci_scan_slot(bus, PCI_DEVFN(slot->device, 0));
> >
> > max = acpiphp_max_busnr(bus);
> > for (pass = 0; pass < 2; pass++) {
>
> I think this is two logical changes: the change below looks like it
> could by done by itself first, followed by the change above.
Indeed. We'll going to drop the second change completely.
>
> > @@ -707,8 +702,11 @@ static int __ref enable_device(struct acpiphp_slot *slot)
> > dev->hdr_type == PCI_HEADER_TYPE_CARDBUS) {
> > max = pci_scan_bridge(bus, dev, max, pass);
> > if (pass && dev->subordinate) {
> > - check_hotplug_bridge(slot, dev);
> > - pcibios_resource_survey_bus(dev->subordinate);
> > + if (!dev->subordinate->is_added) {
> > + check_hotplug_bridge(slot, dev);
> > + pcibios_resource_survey_bus(
> > + dev->subordinate);
>
> It's a shame that pcibios_resource_survey_bus() can't be called twice.
> It would be nice if it were smart enough to notice on the second call
> that "oh, resources have already been assigned, so there's nothing
> more to be done." Did you look to see whether that's feasible?
I didn't but now that you mentioned I went and checked. I'm pretty sure we
can handle it there in the next revision and drop this change.
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