Add Intel ACPI IGD OpRegion support

This adds the support necessary for allowing ACPI backlight control to
work on some newer Intel-based graphics systems. Tested on Thinkpad T61
and HP 2510p hardware.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 6c99aab..d95eca2 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -371,6 +371,8 @@
 
 	i915_save_vga(dev);
 
+	intel_opregion_free(dev);
+
 	if (state.event == PM_EVENT_SUSPEND) {
 		/* Shut down the device */
 		pci_disable_device(dev->pdev);
@@ -532,6 +534,8 @@
 
 	i915_restore_vga(dev);
 
+	intel_opregion_init(dev);
+
 	return 0;
 }