tree: https://git.kernel.org/pub/scm/linux/kernel/git/hid/hid.git for-5.18/apple head: c5f09b1b45cbb90147846f82ec0489789c99667e commit: 9018eacbe623b2c3535da37035e5f22d3d70b6ce [6/8] HID: apple: Add support for keyboard backlight on certain T2 Macs. config: csky-defconfig (https://download.01.org/0day-ci/archive/20220217/202202170730.8pPvrRAz-lk...) compiler: csky-linux-gcc (GCC) 11.2.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://git.kernel.org/pub/scm/linux/kernel/git/hid/hid.git/commit/?id=90... git remote add hid https://git.kernel.org/pub/scm/linux/kernel/git/hid/hid.git git fetch --no-tags hid for-5.18/apple git checkout 9018eacbe623b2c3535da37035e5f22d3d70b6ce # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=csky SHELL=/bin/bash If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): csky-linux-ld: drivers/hid/hid-apple.o: in function `apple_backlight_init.isra.0': hid-apple.c:(.text+0x2e6): undefined reference to `devm_led_classdev_register_ext' --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org