tree: https://git.kernel.org/pub/scm/linux/kernel/git/jirislaby/linux.git devel head: e07aaf938405b723f435206c00fcc50a11a70399 commit: f22cec00dbd414f61389ec805a29e70e55b9d84a [8/19] mxser: switch to uart_driver config: i386-buildonly-randconfig-r002-20211208 (https://download.01.org/0day-ci/archive/20211208/202112082345.v46Z3TI4-lk...) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 097a1cb1d5ebb3a0ec4bcaed8ba3ff6a8e33c00a) 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/jirislaby/linux.git/commi... git remote add jirislaby https://git.kernel.org/pub/scm/linux/kernel/git/jirislaby/linux.git git fetch --no-tags jirislaby devel git checkout f22cec00dbd414f61389ec805a29e70e55b9d84a # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/tty/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): drivers/tty/mxser.c:377:13: warning: unused function 'mxser_must_no_sw_flow_control' [-Wunused-function] static void mxser_must_no_sw_flow_control(unsigned long baseio) ^ drivers/tty/mxser.c:591:13: warning: unused function 'mxser_change_speed' [-Wunused-function] static void mxser_change_speed(struct tty_struct *tty, ^ drivers/tty/mxser.c:1394:13: warning: unused function 'mxser_start' [-Wunused-function] static void mxser_start(struct tty_struct *tty) ^ static const struct uart_ops mxser_ops = { ^ 4 warnings generated. vim +/mxser_ops +1784 drivers/tty/mxser.c 1783 1785 .tx_empty = mxser_tx_empty, 1786 //.get_mctrl = mxser_get_mctrl, 1787 //.set_mctrl = mxser_set_mctrl, 1788 .stop_tx = mxser_stop_tx, 1789 .start_tx = mxser_start_tx, 1790 .stop_rx = mxser_stop_rx, 1791 .break_ctl = mxser_break_ctl, 1792 //.startup = mxser_startup, 1793 //.shutdown = mxser_shutdown, 1794 .set_termios = mxser_set_termios, 1795 //.pm = mxser_pm, 1796 //.type = mxser_type, 1797 //.release_port = mxser_release_port, 1798 //.request_port = mxser_request_port, 1799 //.config_port = mxser_config_port, 1800 //.verify_port = mxser_verify_port, 1801 }; 1802 1803 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org