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path: root/drivers/pci/hotplug/acpi_pcihp.c
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Diffstat (limited to 'drivers/pci/hotplug/acpi_pcihp.c')
-rw-r--r--drivers/pci/hotplug/acpi_pcihp.c36
1 files changed, 19 insertions, 17 deletions
diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
index 5bd6c1573295..6b7c1ed58e7e 100644
--- a/drivers/pci/hotplug/acpi_pcihp.c
+++ b/drivers/pci/hotplug/acpi_pcihp.c
@@ -74,20 +74,6 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev)
struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
/*
- * Per PCI firmware specification, we should run the ACPI _OSC
- * method to get control of hotplug hardware before using it. If
- * an _OSC is missing, we look for an OSHP to do the same thing.
- * To handle different BIOS behavior, we look for _OSC on a root
- * bridge preferentially (according to PCI fw spec). Later for
- * OSHP within the scope of the hotplug controller and its parents,
- * up to the host bridge under which this controller exists.
- */
- if (shpchp_is_native(pdev))
- return 0;
-
- /* If _OSC exists, we should not evaluate OSHP */
-
- /*
* If there's no ACPI host bridge (i.e., ACPI support is compiled
* into the kernel but the hardware platform doesn't support ACPI),
* there's nothing to do here.
@@ -97,9 +83,25 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev)
if (!root)
return 0;
- if (root->osc_support_set)
- goto no_control;
+ /*
+ * If _OSC exists, it determines whether we're allowed to manage
+ * the SHPC. We executed it while enumerating the host bridge.
+ */
+ if (root->osc_support_set) {
+ if (host->native_shpc_hotplug)
+ return 0;
+ return -ENODEV;
+ }
+ /*
+ * In the absence of _OSC, we're always allowed to manage the SHPC.
+ * However, if an OSHP method is present, we must execute it so the
+ * firmware can transfer control to the OS, e.g., direct interrupts
+ * to the OS instead of to the firmware.
+ *
+ * N.B. The PCI Firmware Spec (r3.2, sec 4.8) does not endorse
+ * searching up the ACPI hierarchy, so the loops below are suspect.
+ */
handle = ACPI_HANDLE(&pdev->dev);
if (!handle) {
/*
@@ -128,7 +130,7 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev)
if (ACPI_FAILURE(status))
break;
}
-no_control:
+
pci_info(pdev, "Cannot get control of SHPC hotplug\n");
kfree(string.pointer);
return -ENODEV;