1 files changed, 41 insertions, 15 deletions

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index c412fdb28d34..513e7230e3d0 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -470,6 +470,16 @@ static int __init acpi_bus_init_irq(void)
 	return 0;
 }
 
+/**
+ * acpi_early_init - Initialize ACPICA and populate the ACPI namespace.
+ *
+ * The ACPI tables are accessible after this, but the handling of events has not
+ * been initialized and the global lock is not available yet, so AML should not
+ * be executed at this point.
+ *
+ * Doing this before switching the EFI runtime services to virtual mode allows
+ * the EfiBootServices memory to be freed slightly earlier on boot.
+ */
 void __init acpi_early_init(void)
 {
 	acpi_status status;
@@ -533,26 +543,42 @@ void __init acpi_early_init(void)
 		acpi_gbl_FADT.sci_interrupt = acpi_sci_override_gsi;
 	}
 #endif
+	return;
+
+ error0:
+	disable_acpi();
+}
+
+/**
+ * acpi_subsystem_init - Finalize the early initialization of ACPI.
+ *
+ * Switch over the platform to the ACPI mode (if possible), initialize the
+ * handling of ACPI events, install the interrupt and global lock handlers.
+ *
+ * Doing this too early is generally unsafe, but at the same time it needs to be
+ * done before all things that really depend on ACPI.  The right spot appears to
+ * be before finalizing the EFI initialization.
+ */
+void __init acpi_subsystem_init(void)
+{
+	acpi_status status;
+
+	if (acpi_disabled)
+		return;
 
 	status = acpi_enable_subsystem(~ACPI_NO_ACPI_ENABLE);
 	if (ACPI_FAILURE(status)) {
 		printk(KERN_ERR PREFIX "Unable to enable ACPI\n");
-		goto error0;
+		disable_acpi();
+	} else {
+		/*
+		 * If the system is using ACPI then we can be reasonably
+		 * confident that any regulators are managed by the firmware
+		 * so tell the regulator core it has everything it needs to
+		 * know.
+		 */
+		regulator_has_full_constraints();
 	}
-
-	/*
-	 * If the system is using ACPI then we can be reasonably
-	 * confident that any regulators are managed by the firmware
-	 * so tell the regulator core it has everything it needs to
-	 * know.
-	 */
-	regulator_has_full_constraints();
-
-	return;
-
-      error0:
-	disable_acpi();
-	return;
 }
 
 static int __init acpi_bus_init(void)