Hi Lee, I love your patch! Yet something to improve: [auto build test ERROR on ljones-mfd/for-mfd-next] [also build test ERROR on v5.8-rc1 next-20200617] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Lee-Jones/mfd-Add-I2C-based-Syst... base: https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git for-mfd-next config: x86_64-allmodconfig (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 487ca07fcc75d52755c9fe2ee05bcb3b6eeeec44) 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 # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 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 >>, old ones prefixed by <<): struct regmap *syscon_i2c_to_regmap(struct i2c_client *client) ^ include/linux/mfd/syscon-i2c.h:20:30: note: previous definition is here static inline struct regmap *syscon_i2c_to_regmap(struct i2c_client *client) ^ 1 error generated. vim +/syscon_i2c_to_regmap +86 drivers/mfd/syscon-i2c.c 85 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org