reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/wens/linux.git/commit/?id=e21fd10d1aa3f6556ed35a5af16f85a9ad14c29a
        git remote add wens https://git.kernel.org/pub/scm/linux/kernel/git/wens/linux.git
        git fetch --no-tags wens mtk-wip
        git checkout e21fd10d1aa3f6556ed35a5af16f85a9ad14c29a
        # 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/i2c/