AG71XX_REG_TX_CTRL
ag71xx_wr(ag, AG71XX_REG_TX_CTRL, TX_CTRL_TXE);
ag71xx_wr(ag, AG71XX_REG_TX_CTRL, 0);
tx = ag71xx_rr(ag, AG71XX_REG_TX_CTRL) & TX_CTRL_TXE;
ag71xx_wr(ag, AG71XX_REG_TX_CTRL, 0);