reproduce:
        git checkout e90c9612ac3969cb8206029a26bcd2b6f5d4a942
        b4 shazam https://lore.kernel.org/r/20241220-media-rpi-hevc-dec-v1-5-0ebcc04ed42e@raspberrypi.com
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 2.4.4
        make htmldocs