1 files changed, 38 insertions, 21 deletions

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 77cd19697b1e..c34713112520 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -374,21 +374,32 @@ out:
 EXPORT_SYMBOL_GPL(acpi_get_pci_dev);
 
 /**
- * acpi_pci_osc_control_set - commit requested control to Firmware
- * @handle: acpi_handle for the target ACPI object
- * @flags: driver's requested control bits
+ * acpi_pci_osc_control_set - Request control of PCI root _OSC features.
+ * @handle: ACPI handle of a PCI root bridge (or PCIe Root Complex).
+ * @mask: Mask of _OSC bits to request control of, place to store control mask.
+ * @req: Mask of _OSC bits the control of is essential to the caller.
  *
- * Attempt to take control from Firmware on requested control bits.
+ * Run _OSC query for @mask and if that is successful, compare the returned
+ * mask of control bits with @req.  If all of the @req bits are set in the
+ * returned mask, run _OSC request for it.
+ *
+ * The variable at the @mask address may be modified regardless of whether or
+ * not the function returns success.  On success it will contain the mask of
+ * _OSC bits the BIOS has granted control of, but its contents are meaningless
+ * on failure.
  **/
-acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 flags)
+acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
 {
+        struct acpi_pci_root *root;
         acpi_status status;
-        u32 control_req, result, capbuf[3];
+        u32 ctrl, capbuf[3];
         acpi_handle tmp;
-        struct acpi_pci_root *root;
 
-        control_req = (flags & OSC_PCI_CONTROL_MASKS);
-        if (!control_req)
+        if (!mask)
+                return AE_BAD_PARAMETER;
+
+        ctrl = *mask & OSC_PCI_CONTROL_MASKS;
+        if ((ctrl & req) != req)
                 return AE_TYPE;
 
         root = acpi_pci_find_root(handle);
@@ -400,27 +411,33 @@ acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 flags)
                 return status;
 
         mutex_lock(&osc_lock);
+
+        *mask = ctrl | root->osc_control_set;
         /* No need to evaluate _OSC if the control was already granted. */
-        if ((root->osc_control_set & control_req) == control_req)
+        if ((root->osc_control_set & ctrl) == ctrl)
                 goto out;
 
-        /* Need to query controls first before requesting them */
-        flags = control_req;
-        status = acpi_pci_query_osc(root, root->osc_support_set, &flags);
-        if (ACPI_FAILURE(status))
-                goto out;
+        /* Need to check the available controls bits before requesting them. */
+        while (*mask) {
+                status = acpi_pci_query_osc(root, root->osc_support_set, mask);
+                if (ACPI_FAILURE(status))
+                        goto out;
+                if (ctrl == *mask)
+                        break;
+                ctrl = *mask;
+        }
 
-        if (flags != control_req) {
+        if ((ctrl & req) != req) {
                 status = AE_SUPPORT;
                 goto out;
         }
 
         capbuf[OSC_QUERY_TYPE] = 0;
         capbuf[OSC_SUPPORT_TYPE] = root->osc_support_set;
-        capbuf[OSC_CONTROL_TYPE] = root->osc_control_set | control_req;
-        status = acpi_pci_run_osc(handle, capbuf, &result);
+        capbuf[OSC_CONTROL_TYPE] = ctrl;
+        status = acpi_pci_run_osc(handle, capbuf, mask);
         if (ACPI_SUCCESS(status))
-                root->osc_control_set = result;
+                root->osc_control_set = *mask;
 out:
         mutex_unlock(&osc_lock);
         return status;
@@ -551,8 +568,8 @@ 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,
-                                          OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
+        flags = OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL;
+        status = acpi_pci_osc_control_set(root->device->handle, &flags, flags);
 
         if (ACPI_FAILURE(status)) {
                 printk(KERN_INFO "Unable to assume PCIe control: Disabling ASPM\n");