PCI: Allow additional bus numbers for hotplug bridges
A user may hot add a switch requiring more than one bus to enumerate. This
previously required a system reboot if BIOS did not sufficiently pad the
bus resource, which they frequently don't do.
Add a kernel parameter so a user can specify the minimum number of bus
numbers to reserve for a hotplug bridge's subordinate buses so rebooting
won't be necessary.
The default is 1, which is equivalent to previous behavior.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8e3ef72..f680099 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2077,6 +2077,15 @@
}
/*
+ * Make sure a hotplug bridge has at least the minimum requested
+ * number of buses.
+ */
+ if (bus->self && bus->self->is_hotplug_bridge && pci_hotplug_bus_size) {
+ if (max - bus->busn_res.start < pci_hotplug_bus_size - 1)
+ max = bus->busn_res.start + pci_hotplug_bus_size - 1;
+ }
+
+ /*
* We've scanned the bus and so we know all about what's on
* the other side of any bridges that may be on this bus plus
* any devices.