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>

drivers/gpu/drm/i915/i915_drv.c

@@ -371,6 +371,8 @@ static int i915_suspend(struct drm_device *dev, pm_message_t state)
 
 	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 @@ static int i915_resume(struct drm_device *dev)
 
 	i915_restore_vga(dev);
 
+	intel_opregion_init(dev);
+
 	return 0;
 }