reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight.git/commit/?id=0eda30af58809224d80dc3bf3f368fc677fe8c08
        git remote add lee-backlight https://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight.git
        git fetch --no-tags lee-backlight for-backlight-next
        git checkout 0eda30af58809224d80dc3bf3f368fc677fe8c08
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 2.4.4
        make htmldocs