MXS_AUART_DMA_TX_SYNC
clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);
if (test_and_set_bit(MXS_AUART_DMA_TX_SYNC, &s->flags))
clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);
clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);