reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux.git/commit/?id=a060b8c511abb0997381b397e52149a5e3e5259a
        git remote add brgl https://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux.git
        git fetch --no-tags brgl gpio/for-next
        git checkout a060b8c511abb0997381b397e52149a5e3e5259a

        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=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash drivers/gpio/