DTG - device tree generator limitations

Hello,

In documentation it is said:

"There are a number of components that can be connected to HPS portion of the soc (https://rocketboards.org/foswiki/view/documentation/soc) FPGA that require Device Tree information for their drivers. Since Qsys not aware of the components outside the FPGA fabric, this information must be provided to the Device Tree Generator."

I am not sure I understand this, what exactly should be manually added to dts file ?

Can anyone help understanding DTG limitations with dts ?

Regards,

Ran