WIP: T818 support

[schlegp]

Hi there. The T818 has the same device ID as the T248 (b696) so it is immediately picked up by hid-tmff2 and usable. I recently noticed that it's feeling different than on Windows, so I decided to capture USB packets and check if I can see any differences between Linux and Windows.

This issue is intended as a place for me to gather my findings and for people to chime in if they already have some information.

To find packets differing between Windows and Linux I for now resorted to recording USB packets while running rFactor 2 and comparing the used commands. Most of them are the same but there is one command that is sent a few times that does not seem to be sent by hid-tmff-new.

60 00 --- Default Header 01 --- ID 0b --- Unknown Command 00 00 37 fd --- Unknown values 00 00 ff ff --- Unknown vlaues 00 80 --- Unknown values

I was unable to recreate this command with fedit.exe for now, so I have no clue what it does. I don't quite understand the code inside t248.c yet, though, so it might be that it was already deciphered.

If anyone cares to chip in or help out, feel free!