VOP_SYS_CTRL
val = RD4(sc, VOP_SYS_CTRL);
WR4(sc, VOP_SYS_CTRL, val);
val = RD4(sc, VOP_SYS_CTRL);
WR4(sc, VOP_SYS_CTRL, val);
val = RD4(sc, VOP_SYS_CTRL);
WR4(sc, VOP_SYS_CTRL, val);
val = RD4(sc, VOP_SYS_CTRL);
WR4(sc, VOP_SYS_CTRL, val);