Hi Tzung-Bi, Thank you for the patch! Yet something to improve: [auto build test ERROR on chrome-platform/for-next] [also build test ERROR on robh/for-next lee-mfd/for-mfd-next v5.17-rc4 next-20220214] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Tzung-Bi-Shih/platform-chrome-cr... base: https://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux.git for-next config: i386-randconfig-a001 ( https://download.01.org/0day-ci/archive/20220214/202202142320.uQhUtcwm-lk... ) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/8f5fc05563b71136a2ab6f2cb5a068a15... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Tzung-Bi-Shih/platform-chrome-cros_kbd_led_backlight-add-EC-PWM-backend/20220214-133805 git checkout 8f5fc05563b71136a2ab6f2cb5a068a152267965 # save the config file to linux build tree mkdir build_dir make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/platform/chrome/ 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 >>): >> drivers/platform/chrome/cros_kbd_led_backlight.c:168:34: error: 'keyboard_led_of_match' defined but not used [-Werror=unused-const-variable=] 168 | static const struct of_device_id keyboard_led_of_match[] = { | ^~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors vim +/keyboard_led_of_match +168 drivers/platform/chrome/cros_kbd_led_backlight.c 167 > 168 static const struct of_device_id keyboard_led_of_match[] = { 169 { 170 .compatible = "google,cros-kbd-led-backlight", 171 }, 172 {} 173 }; 174 MODULE_DEVICE_TABLE(of, keyboard_led_of_match); 175 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org