diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 54e1796d2953..9b5b21ad8378 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -146,7 +146,7 @@ void sun4i_tcon_set_mux(struct sun4i_tcon *tcon, int channel,
 }
 EXPORT_SYMBOL(sun4i_tcon_set_mux);
 
-static int sun4i_tcon_get_clk_delay(struct drm_display_mode *mode,
+static int sun4i_tcon_get_clk_delay(const struct drm_display_mode *mode,
 				    int channel)
 {
 	int delay = mode->vtotal - mode->vdisplay;