Connman is targeted towards mobile network management. It’s strength is in dynamic network configurations, and making use of various (wired and wireless) network technologies.
While it is possible to use connman to configure a static IP address for an ethernet network device, it is not really suited for that use case. I recommend to use systemd-networkd, which is part of our BSP too.
systemd-networkd allows to use a simple configuration files. We already make use of networkd to configure the USB RNDIS network interface. You can add another configuration file inside /etc/systemd/network/ (e.g. called wired.network)…
…and integrate it similar to the existing rndis.network file, see bbappend and files sub directory of our systemd configuration: systemd « recipes-core - meta-toradex.git - oe-core BSP layer (obsolete)
To avoid conflicts with connman, remove connman from the image by removing CONMANPKGS from IMAGE_INSTALL in the image recipe:
(I recommend to test your configuration on a standard image first. You can remove connman using
opkg remove connman connman-gnome).