diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index 48c222d..f8f9ae6 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -845,7 +845,7 @@ static int vop_crtc_enable_vblank(struct drm_crtc *crtc)
 	struct vop *vop = to_vop(crtc);
 	unsigned long flags;
 
-	if (!vop->is_enabled)
+	if (WARN_ON(!vop->is_enabled))
 		return -EPERM;
 
 	spin_lock_irqsave(&vop->irq_lock, flags);