Well...
Unfortuantely for some reasons I am facing issues...
Compilation is OK. The image files look OK, running DTC shows the right DTS was selected from kernel, but for some reason the board refuse to boot, having intermittent blue light.
I also tried to move the DTB file in a ROCKPI image and change the extlinux file to point to the right DTB .... Same result.... I suspect something wrong with this DTS but
I don't know how to debug that.