[PATCH 2/6] PCI: acpiphp: enable_device(): rescan even if no new devices on slot

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

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

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@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 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++) {
@@ -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);
+					}
 					__pci_bus_size_bridges(dev->subordinate,
 							       &add_list);
 				}
@@ -742,8 +740,6 @@ static int __ref enable_device(struct acpiphp_slot *slot)
 		}
 	}
 
-
- err_exit:
 	return 0;
 }
 
-- 
1.8.3.1