reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/?id=3992072f44910c0eb3fdb3cb09540b60f04cd04b
        git remote add jic23-iio https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git
        git fetch --no-tags jic23-iio testing
        git checkout 3992072f44910c0eb3fdb3cb09540b60f04cd04b

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash drivers/iio/adc/