reproduce:
        git remote add drm-amdgpu https://gitlab.freedesktop.org/drm/amdgpu/kernel
        git fetch --no-tags drm-amdgpu drm-amdgpu-next
        git checkout 7e9fca772695c65f97493272e2e7cd475f202965
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs