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);