reproduce:
        git checkout a08b2b34239e63bd839078de98911d3653cdab83
        b4 shazam https://lore.kernel.org/r/20250528-hdp-upstream-v4-4-7e9b3ad2036d@foss.st.com
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 2.4.4
        make htmldocs