Hi Angelo, I love your patch! Perhaps something to improve: [auto build test WARNING on usb-serial/usb-next] [also build test WARNING on peter.chen-usb/ci-for-usb-next balbi-usb/testing/next usb/usb-testing v5.8-rc5 next-20200717] [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/Angelo-Dureghello/USB-serial-add... base: https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial.git usb-next config: s390-randconfig-s032-20200719 (attached as .config) compiler: s390-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # apt-get install sparse # sparse version: v0.6.2-49-g707c5017-dirty # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=s390 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) drivers/usb/serial/xr21v1412.c:71:9: sparse: sparse: preprocessor token PARITY_NONE redefined drivers/usb/serial/xr21v1412.c:149:42: sparse: sparse: Using plain integer as NULL pointer vim +24 include/uapi/linux/hdlc/ioctl.h eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 21 eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 22 eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 23 #define PARITY_DEFAULT 0 /* Default setting */ eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 @24 #define PARITY_NONE 1 /* No parity */ eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 25 #define PARITY_CRC16_PR0 2 /* CRC16, initial value 0x0000 */ eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 26 #define PARITY_CRC16_PR1 3 /* CRC16, initial value 0xFFFF */ eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 27 #define PARITY_CRC16_PR0_CCITT 4 /* CRC16, initial 0x0000, ITU-T version */ eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 28 #define PARITY_CRC16_PR1_CCITT 5 /* CRC16, initial 0xFFFF, ITU-T version */ eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 29 #define PARITY_CRC32_PR0_CCITT 6 /* CRC32, initial value 0x00000000 */ eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 30 #define PARITY_CRC32_PR1_CCITT 7 /* CRC32, initial value 0xFFFFFFFF */ eb2a2fd91f7c8a include/linux/hdlc/ioctl.h Krzysztof Halasa 2006-09-26 31 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org