reproduce:
        git checkout ffd294d346d185b70e28b1a28abe367bbfe53c04
        b4 shazam https://lore.kernel.org/r/20250122-socfpga_sip_svc_misc-v1-2-cbdcd034ae34@intel.com
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 2.4.4
        make htmldocs