[PATCH 2/6] PCI: Pass available buses also when the bridge is already configured

[Mika Westerberg <mika.westerberg@linux.intel.com>]

If some part of the PCI topology is already configured (by the boot
firmware) but not all, and it includes hotplug bridges, we may need to
extend the bus resources of those bridges to accommondate any future
hotplugs too - in the same way we already do with normal hotplug case.

For this reason pass the available busses to pci_scan_child_bus_extend()
even when the bridge in question is already configured. This allows the
bus allocation code to use these available buses to extend the possible
hotplug bridges below.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216000
Reported-by: Chris Chiu <chris.chiu@canonical.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/pci/probe.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 4f940dcd102c..86130926a74f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1297,7 +1297,7 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 
 	if ((secondary || subordinate) && !pcibios_assign_all_busses() &&
 	    !is_cardbus && !broken) {
-		unsigned int cmax;
+		unsigned int cmax, buses;
 
 		/*
 		 * Bus already configured by firmware, process it in the
@@ -1322,7 +1322,8 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 			child->bridge_ctl = bctl;
 		}
 
-		cmax = pci_scan_child_bus(child);
+		buses = subordinate - secondary;
+		cmax = pci_scan_child_bus_extend(child, buses);
 		if (cmax > subordinate)
 			pci_warn(dev, "bridge has subordinate %02x but max busn %02x\n",
 				 subordinate, cmax);
-- 
2.35.1