Yesterday I tried to apply latest RT patch to the radxa’s kernel repo. The result is 15 files with rejected hunks (about 10 Kb in total, RT patch size is 1Mb). All rejected hunks must be added manually. And kernel building results is undefined (:
One more possible solution - using the develop-4.4-rt176 branch from the upstream rockchip repo.
Here is my topic about this - What about RT linux?