1 files changed, 38 insertions, 1 deletions

diff --git a/drivers/acpi/acpica/evxfregn.c b/drivers/acpi/acpica/evxfregn.c
index 541cbc1544d5..00cd95692a91 100644
--- a/drivers/acpi/acpica/evxfregn.c
+++ b/drivers/acpi/acpica/evxfregn.c
@@ -6,7 +6,7 @@
  *****************************************************************************/
 
 /*
- * Copyright (C) 2000 - 2010, Intel Corp.
+ * Copyright (C) 2000 - 2011, Intel Corp.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -64,6 +64,12 @@ ACPI_MODULE_NAME("evxfregn")
  *
  * DESCRIPTION: Install a handler for all op_regions of a given space_id.
  *
+ * NOTE: This function should only be called after acpi_enable_subsystem has
+ * been called. This is because any _REG methods associated with the Space ID
+ * are executed here, and these methods can only be safely executed after
+ * the default handlers have been installed and the hardware has been
+ * initialized (via acpi_enable_subsystem.)
+ *
  ******************************************************************************/
 acpi_status
 acpi_install_address_space_handler(acpi_handle device,
@@ -104,6 +110,37 @@ acpi_install_address_space_handler(acpi_handle device,
                 goto unlock_and_exit;
         }
 
+        /*
+         * For the default space_iDs, (the IDs for which there are default region handlers
+         * installed) Only execute the _REG methods if the global initialization _REG
+         * methods have already been run (via acpi_initialize_objects). In other words,
+         * we will defer the execution of the _REG methods for these space_iDs until
+         * execution of acpi_initialize_objects. This is done because we need the handlers
+         * for the default spaces (mem/io/pci/table) to be installed before we can run
+         * any control methods (or _REG methods). There is known BIOS code that depends
+         * on this.
+         *
+         * For all other space_iDs, we can safely execute the _REG methods immediately.
+         * This means that for IDs like embedded_controller, this function should be called
+         * only after acpi_enable_subsystem has been called.
+         */
+        switch (space_id) {
+        case ACPI_ADR_SPACE_SYSTEM_MEMORY:
+        case ACPI_ADR_SPACE_SYSTEM_IO:
+        case ACPI_ADR_SPACE_PCI_CONFIG:
+        case ACPI_ADR_SPACE_DATA_TABLE:
+
+                if (!acpi_gbl_reg_methods_executed) {
+
+                        /* We will defer execution of the _REG methods for this space */
+                        goto unlock_and_exit;
+                }
+                break;
+
+        default:
+                break;
+        }
+
         /* Run all _REG methods for this address space */
 
         status = acpi_ev_execute_reg_methods(node, space_id);