Actually CONFIG_DRM_GMA3600=y option is needed, but it's not set because it's seen as 'experimental', eventhough on other distros (I've tested meanwhile), it is set and it is working beautifully.
I've tested the same kernel on this type of computers (that needs this option in order to use xorg in modesetting mode), and on other older ones (10 years old that work without).
I didn't notice any problem on any machine because of this 'experimental' option.
I feel I'm stuck, unless:
I go my way in my corner to solve my problem, just to keep using TC on ALL my computers,
make a wish that a TC kernel could be provided, with this option set, and be an 'exceptionnally' exception for the team policy, and start testing TC5 as soon as possible.
thank you for considering this as a request from me, and I think from many others on this forum they didn't show up yet.