Investigate Device Tree Problems (with NVIDIA Xavier NX and a custom board)

I have a NVIDIA Xavier NX (aarch64) with a custom board. It worked well with 4.x kernel and Cboot. Now after migrating to 5.x kernel and UEFI it hangs on boot with the following error: "ParseGicMsiBase: cannot retrieve property 'msi-parent': FDT_ERR_NOTFOUND" I don't have prior experience working with device trees and my question is how can I start investigating this problem. I familiar with the general concept of device trees and how to compile and use them. My lack of knowledge is mainly in the specific properties and values inside the .dts/.dtsi files. I don't know how one decides which properties are needed in each node and what their suitable values. For that reason I don't know how to try and fix my issue. I'm working with a specific SoM and custom board but I think the needed steps and knowledge are general and valid for other cases as well. Because of my lack of experience with this subject I'll be happy to get an answer as much detailed as possible in order to start investigating the issue and learn this subject as well. Thank you very much.