DCR_TFT1
sc->sc_dcr = DCR_LBR | DCR_SBUS | DCR_TFT0 | DCR_TFT1;
#define DCR_TFT24 DCR_TFT1 /* transmit threshold 24 bytes */
#define DCR_TFT28 (DCR_TFT1|DCR_TFT0) /* transmit threshold 28 bytes */