+static void intel_setup_cadls(struct drm_device *dev)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ struct intel_opregion *opregion = &dev_priv->opregion;
+ int i = 0;
+ u32 disp_id;
+
+ /* Initialize the CADL field by duplicating the DIDL values.
+ * Technically, this is not always correct as display outputs may exist,
+ * but not active. This initialization is necessary for some Clevo
+ * laptops that check this field before processing the brightness and
+ * display switching hotkeys. Just like DIDL, CADL is NULL-terminated if
+ * there are less than eight devices. */
+ do {
+ disp_id = ioread32(&opregion->acpi->didl[i]);
+ iowrite32(disp_id, &opregion->acpi->cadl[i]);
+ } while (++i < 8 && disp_id != 0);
+}
+