diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.c b/drivers/gpu/drm/rockchip/cdn-dp-reg.c
index 963d8abec463eb74660bbe356372e184e71236cc..b14d211f6c21739766ed8707b8ffd2e2d30e7f18 100644
--- a/drivers/gpu/drm/rockchip/cdn-dp-reg.c
+++ b/drivers/gpu/drm/rockchip/cdn-dp-reg.c
@@ -671,6 +671,10 @@ int cdn_dp_config_video(struct cdn_dp_device *dp)
 		rem = do_div(symbol, 1000);
 		if (tu_size_reg > 64) {
 			ret = -EINVAL;
+			DRM_DEV_ERROR(dp->dev,
+				      "tu error, clk:%d, lanes:%d, rate:%d\n",
+				      mode->clock, dp->link.num_lanes,
+				      link_rate);
 			goto err_config_video;
 		}
 	} while ((symbol <= 1) || (tu_size_reg - symbol < 4) ||