PCI/ACPI: Reserve firmware-allocated resources for hot-added root buses

Firmware may have assigned PCI BARs for hot-added devices, so reserve
those resources before trying to allocate more.

[bhelgaas: move empty weak definition here]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 7928d4dc7056..dcbe9660e756 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -650,8 +650,10 @@ static int acpi_pci_root_start(struct acpi_device *device)
         struct acpi_pci_root *root = acpi_driver_data(device);
         struct acpi_pci_driver *driver;
 
-        if (system_state != SYSTEM_BOOTING)
+        if (system_state != SYSTEM_BOOTING) {
+                pcibios_resource_survey_bus(root->bus);
                 pci_assign_unassigned_bus_resources(root->bus);
+        }
 
         mutex_lock(&acpi_pci_root_lock);
         list_for_each_entry(driver, &acpi_pci_drivers, node)