reproduce (this is a W=1 build):
        # https://github.com/krzk/linux/commit/ad3c44509074f9f896bcdec6d6b1f051b169dcf6
        git remote add krzk-github https://github.com/krzk/linux
        git fetch --no-tags krzk-github n/audio-sm8650-on-neil-codelinaro-topic-sm8650-upstream-integ
        git checkout ad3c44509074f9f896bcdec6d6b1f051b169dcf6
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/spmi/