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-20200713] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use 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: parisc-randconfig-s031-20200714 (attached as .config) compiler: hppa-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: v0.6.2-41-g14e84ffc-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=parisc 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 >>) vim +149 drivers/usb/serial/xr21v1412.c 136 137 static int xr21v1412_xr_set_register(struct usb_device *udev, u16 reg, u16 val) 138 { 139 int retry = REG_SET_RETRY; 140 int status, size; 141 142 while (retry--) { 143 status = usb_control_msg(udev, 144 usb_sndctrlpipe(udev, 0), 145 REQ_SET_REG, 146 REQ_TYPE_XR_SET_REG, 147 val & 0xff, 148 reg, 150 0, 151 USB_CTRL_SET_TIMEOUT); 152 if (status < 0) { 153 status = usb_translate_errors(status); 154 if (status == -EIO) 155 continue; 156 } else if (status != size) { 157 /* Retry on short transfers */ 158 status = -EIO; 159 continue; 160 } else { 161 status = 0; 162 } 163 164 break; 165 } 166 167 if (status) { 168 dev_err(&udev->dev, "failed to set register 0x%x: %d\n", 169 reg, status); 170 } 171 172 return status; 173 } 174 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org