diff options
Diffstat (limited to 'pci-acpi-disable-aspm-if-no-osc.patch')
| -rw-r--r-- | pci-acpi-disable-aspm-if-no-osc.patch | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/pci-acpi-disable-aspm-if-no-osc.patch b/pci-acpi-disable-aspm-if-no-osc.patch new file mode 100644 index 000000000..044f38964 --- /dev/null +++ b/pci-acpi-disable-aspm-if-no-osc.patch @@ -0,0 +1,53 @@ +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 + +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_runtime.h> + #include <linux/pci.h> + #include <linux/pci-acpi.h> ++#include <linux/pci-aspm.h> + #include <linux/acpi.h> + #include <linux/slab.h> + #include <acpi/acpi_bus.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(); ++ } ++ + pci_acpi_add_bus_pm_notifier(device, root->bus); + if (device->wakeup.flags.run_wake) + device_set_run_wake(root->bus->bridge, true); |