A_TP_TCP_BACKOFF_REG0
t3_write_reg(adap, A_TP_TCP_BACKOFF_REG0, 0x3020100);
r = A_TP_TCP_BACKOFF_REG0 + (idx & ~3);
t4_set_reg_field(sc, A_TP_TCP_BACKOFF_REG0 + (i & ~3),