--- src/r6xx_accel.c.orig	2010-04-01 04:37:46.000000000 +0200
+++ src/r6xx_accel.c	2010-06-21 23:23:11.000000000 +0200
@@ -1322,6 +1351,8 @@
     }
 #endif 
 
-    r600_finish_op(pScrn, vert_size);
-    r600_cp_start(pScrn);
+    if (accel_state->vb_start_op != -1) {
+	r600_finish_op(pScrn, vert_size);
+	r600_cp_start(pScrn);
+    }
 }