reproduce:
        git checkout 1f97d9dcf53649c41c33227b345a36902cbb08ad
        b4 shazam https://lore.kernel.org/r/20260213-i2c-mux-v5-5-fb2cbf9979b3@gmail.com
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs