commit 885c252ffb059dc493200bdb981bdd21cabe4442
Author: Matthew Garrett <mjg@redhat.com>
Date:   Thu Dec 9 18:31:59 2010 -0500

    PCI: _OSC "supported" field should contain supported features, not enabled ones
    
    From testing with Windows, the call to the PCI root _OSC method includes
    the full set of features supported by the operating system even if the
    hardware has already indicated that it doesn't support ASPM or MSI.
    https://bugzilla.redhat.com/show_bug.cgi?id=638912 is a case where making
    the _OSC call will incorrectly configure the chipset unless the supported
    field has bits 1, 2 and 4 set. Rework the functionality to ensure that
    we match this behaviour.
    
    Signed-off-by: Matthew Garrett <mjg@redhat.com>

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 96668ad..afb5d08 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -450,7 +450,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	struct acpi_pci_root *root;
 	acpi_handle handle;
 	struct acpi_device *child;
-	u32 flags, base_flags;
+	u32 flags;
 
 	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 	if (!root)
@@ -498,10 +498,15 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	device->driver_data = root;
 
 	/*
-	 * All supported architectures that use ACPI have support for
-	 * PCI domains, so we indicate this in _OSC support capabilities.
+	 * Indicate support for various _OSC capabilities. These match
+	 * what the operating system supports, not what the hardware supports,
+	 * so they shouldn't be conditional on functionality that's been
+	 * blacklisted
 	 */
-	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
+	flags = OSC_EXT_PCI_CONFIG_SUPPORT | OSC_ACTIVE_STATE_PWR_SUPPORT |
+		OSC_CLOCK_PWR_CAPABILITY_SUPPORT |
+		OSC_PCI_SEGMENT_GROUPS_SUPPORT | OSC_MSI_SUPPORT;
+
 	acpi_pci_osc_support(root, flags);
 
 	/*
@@ -555,17 +560,6 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	list_for_each_entry(child, &device->children, node)
 		acpi_pci_bridge_scan(child);
 
-	/* Indicate support for various _OSC capabilities. */
-	if (pci_ext_cfg_avail(root->bus->self))
-		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
-	if (pcie_aspm_enabled())
-		flags |= OSC_ACTIVE_STATE_PWR_SUPPORT |
-			OSC_CLOCK_PWR_CAPABILITY_SUPPORT;
-	if (pci_msi_enabled())
-		flags |= OSC_MSI_SUPPORT;
-	if (flags != base_flags)
-		acpi_pci_osc_support(root, flags);
-
 	pci_acpi_add_bus_pm_notifier(device, root->bus);
 	if (device->wakeup.flags.run_wake)
 		device_set_run_wake(root->bus->bridge, true);