FM10K_TDH
buff[idx++] = fm10k_read_reg(hw, FM10K_TDH(i));
head = fm10k_read_reg(hw, FM10K_TDH(ring->reg_idx));
fm10k_read_reg(hw, FM10K_TDH(tx_ring->reg_idx)),
fm10k_write_reg(hw, FM10K_TDH(reg_idx), 0);