diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index f74523a..8eb3630 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -797,6 +797,10 @@
 extern struct drm_display_mode *drm_gtf_mode(struct drm_device *dev,
 				int hdisplay, int vdisplay, int vrefresh,
 				bool interlaced, int margins);
+extern struct drm_display_mode *drm_gtf_mode_complex(struct drm_device *dev,
+				int hdisplay, int vdisplay, int vrefresh,
+				bool interlaced, int margins, int GTF_M,
+				int GTF_2C, int GTF_K, int GTF_2J);
 extern int drm_add_modes_noedid(struct drm_connector *connector,
 				int hdisplay, int vdisplay);