QMC_BD_TX_R
qmc_write16(&bd->cbd_sc, ctrl & ~(QMC_BD_TX_UB | QMC_BD_TX_R));
if (ctrl & (QMC_BD_TX_R | QMC_BD_TX_UB)) {
if (!(ctrl & (QMC_BD_TX_R | QMC_BD_TX_I)) && bd == chan->txbd_done) {
ctrl |= (QMC_BD_TX_R | QMC_BD_TX_UB);
while (!(ctrl & QMC_BD_TX_R)) {