MLXSW_I2C_READ_MSG
MLXSW_I2C_READ_MSG(client, addr_buf, buf, len);
MLXSW_I2C_READ_MSG(client, addr_buf, buf, MLXSW_I2C_MBOX_SIZE);
MLXSW_I2C_READ_MSG(client, tran_buf, NULL, 0);