drm/i915: Register ACPI video even when not modesetting

The ACPI video driver defers registration to the i915 driver if the
system supports opregion-mediated backlight control. This registration
was only being performed in the KMS case. Ensure it's done even if we
don't have modesetting enabled.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/i915_opregion.c

@@ -370,11 +370,8 @@ int intel_opregion_init(struct drm_device *dev, int resume)
 	if (mboxes & MBOX_ACPI) {
 		DRM_DEBUG("Public ACPI methods supported\n");
 		opregion->acpi = base + OPREGION_ACPI_OFFSET;
-		if (drm_core_check_feature(dev, DRIVER_MODESET)) {
+		if (drm_core_check_feature(dev, DRIVER_MODESET))
 			intel_didl_outputs(dev);
-			if (!resume)
-				acpi_video_register();
-		}
 	} else {
 		DRM_DEBUG("Public ACPI methods not supported\n");
 		err = -ENOTSUPP;
@@ -391,6 +388,10 @@ int intel_opregion_init(struct drm_device *dev, int resume)
 		opregion->asle = base + OPREGION_ASLE_OFFSET;
 	}
 
+	if (!resume)
+		acpi_video_register();
+
+
 	/* Notify BIOS we are ready to handle ACPI video ext notifs.
 	 * Right now, all the events are handled by the ACPI video module.
 	 * We don't actually need to do anything with them. */