diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 6245add..de82e20 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -685,7 +685,7 @@
 	struct drm_framebuffer *fb = fb_helper->fb;
 	int depth;
 
-	if (var->pixclock != 0)
+	if (var->pixclock != 0 || in_dbg_master())
 		return -EINVAL;
 
 	/* Need to resize the fb object !!! */