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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2019-06-15 02:23:57 +0200
committerBjorn Helgaas <bhelgaas@google.com>2019-06-22 01:11:53 +0200
commita78cf9657ba5426f54aa93a067c10d097944c082 (patch)
treeaa6cbc8b7f5808ff37b46a51ab37de03964fea79 /drivers/acpi/pci_root.c
parentLinux 5.2-rc1 (diff)
downloadlinux-a78cf9657ba5426f54aa93a067c10d097944c082.tar.xz
linux-a78cf9657ba5426f54aa93a067c10d097944c082.zip
PCI/ACPI: Evaluate PCI Boot Configuration _DSM
Evaluate _DSM Function #5, the "PCI Boot Configuration" function. If the result is 0, the OS should preserve any resource assignments made by the firmware. Link: https://lore.kernel.org/r/20190615002359.29577-2-benh@kernel.crashing.org Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [bhelgaas: commit log] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'drivers/acpi/pci_root.c')
-rw-r--r--drivers/acpi/pci_root.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index c36781a9b493..0d57f817ef1e 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -894,6 +894,7 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
int node = acpi_get_node(device->handle);
struct pci_bus *bus;
struct pci_host_bridge *host_bridge;
+ union acpi_object *obj;
info->root = root;
info->bridge = device;
@@ -930,6 +931,17 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
if (!(root->osc_control_set & OSC_PCI_EXPRESS_LTR_CONTROL))
host_bridge->native_ltr = 0;
+ /*
+ * Evaluate the "PCI Boot Configuration" _DSM Function. If it
+ * exists and returns 0, we must preserve any PCI resource
+ * assignments made by firmware for this host bridge.
+ */
+ obj = acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), &pci_acpi_dsm_guid, 1,
+ IGNORE_PCI_BOOT_CONFIG_DSM, NULL);
+ if (obj && obj->type == ACPI_TYPE_INTEGER && obj->integer.value == 0)
+ host_bridge->preserve_config = 1;
+ ACPI_FREE(obj);
+
pci_scan_child_bus(bus);
pci_set_host_bridge_release(host_bridge, acpi_pci_root_release_info,
info);