reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/commit/?id=fafe4f5166bc3d43e28967efb9ea82b1f456b798
        git remote add rafael-pm https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git
        git fetch --no-tags rafael-pm bleeding-edge
        git checkout fafe4f5166bc3d43e28967efb9ea82b1f456b798

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/platform/