55 lines
1.9 KiB
Diff
55 lines
1.9 KiB
Diff
|
From: Matthew Garrett <mjg@redhat.com>
|
||
|
|
Subject: ACPI: Disable ASPM if the platform won't provide _OSC control for PCIe
|
||
|
|
|
||
|
|
ACPI: Disable ASPM if the platform won't provide _OSC control for PCIe
|
||
|
|
|
||
|
|
[ backport to 2.6.32 ]
|
||
|
|
|
||
|
|
The PCI SIG documentation for the _OSC OS/firmware handshaking interface
|
||
|
|
states:
|
||
|
|
|
||
|
|
"If the _OSC control method is absent from the scope of a host bridge
|
||
|
|
device, then the operating system must not enable or attempt to use any
|
||
|
|
features defined in this section for the hierarchy originated by the host
|
||
|
|
bridge."
|
||
|
|
|
||
|
|
The obvious interpretation of this is that the OS should not attempt to use
|
||
|
|
PCIe hotplug, PME or AER - however, the specification also notes that an
|
||
|
|
_OSC method is *required* for PCIe hierarchies, and experimental validation
|
||
|
|
with An Alternative OS indicates that it doesn't use any PCIe functionality
|
||
|
|
if the _OSC method is missing. That arguably means we shouldn't be using
|
||
|
|
MSI or extended config space, but right now our problems seem to be limited
|
||
|
|
to vendors being surprised when ASPM gets enabled on machines when other
|
||
|
|
OSs refuse to do so. So, for now, let's just disable ASPM if the _OSC
|
||
|
|
method doesn't exist or refuses to hand over PCIe capability control.
|
||
|
|
|
||
|
|
Signed-off-by: Matthew Garrett <mjg@redhat.com>
|
||
|
|
---
|
||
|
|
|
||
|
|
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
|
||
|
|
index 4eac593..1f67057 100644
|
||
|
|
--- a/drivers/acpi/pci_root.c
|
||
|
|
+++ b/drivers/acpi/pci_root.c
|
||
|
|
@@ -33,6 +33,7 @@
|
||
|
|
#include <linux/pm.h>
|
||
|
|
#include <linux/pci.h>
|
||
|
|
#include <linux/pci-acpi.h>
|
||
|
|
+#include <linux/pci-aspm.h>
|
||
|
|
#include <linux/acpi.h>
|
||
|
|
#include <acpi/acpi_bus.h>
|
||
|
|
#include <acpi/acpi_drivers.h>
|
||
|
|
@@ -543,6 +544,14 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
|
||
|
|
if (flags != base_flags)
|
||
|
|
acpi_pci_osc_support(root, flags);
|
||
|
|
|
||
|
|
+ status = acpi_pci_osc_control_set(root->device->handle,
|
||
|
|
+ 0);
|
||
|
|
+
|
||
|
|
+ if (status == AE_NOT_EXIST) {
|
||
|
|
+ printk(KERN_INFO "Unable to assume PCIe control: Disabling ASPM\n");
|
||
|
|
+ pcie_no_aspm();
|
||
|
|
+ }
|
||
|
|
+
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
end:
|