diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 9628652e080c..e0596954290b 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -237,6 +237,16 @@ static int __acpi_bus_get_power(struct acpi_device *device, int *state)
 	} else if (result == ACPI_STATE_D3_HOT) {
 		result = ACPI_STATE_D3;
 	}
+
+	/*
+	 * If we were unsure about the device parent's power state up to this
+	 * point, the fact that the device is in D0 implies that the parent has
+	 * to be in D0 too.
+	 */
+	if (device->parent && device->parent->power.state == ACPI_STATE_UNKNOWN
+	    && result == ACPI_STATE_D0)
+		device->parent->power.state = ACPI_STATE_D0;
+
 	*state = result;
 
  out: