You might find this of interest:
- https://forums.developer.nvidia.com/t/issues-building-with-device-tree-changes/274572/2
- https://forums.developer.nvidia.com/t/is-kernel-rebuild-necessary-with-a-new-pinmux/321514/2
- https://forums.developer.nvidia.com/t/how-do-i-develop-drivers-on-jetson/301101/4
- https://forums.developer.nvidia.com/t/sc16is752-serial-expansion-board/266210/11
Btw, starting with L4T R36.x (see “head -n 1 /etc/nv_tegra_release”) the kernel switched to mainline. As a result the default configuration changes from tegra_defconfig to just defconfig.