FIFO_SIZE
while (sc->txidx < sc->txlen && sc->fifocnt < FIFO_SIZE) {
val = I2S_INTCR_TFT(FIFO_SIZE/2);
val |= I2S_INTCR_RFT(FIFO_SIZE/2);
if (count > FIFO_SIZE - 1)
count = FIFO_SIZE - 1;