Hi Yoshihiro, I love your patch! Perhaps something to improve: [auto build test WARNING on next-20220909] [also build test WARNING on v6.0-rc4] [cannot apply to geert-renesas-devel/next net-next/master net/master linus/master v6.0-rc4 v6.0-rc3 v6.0-rc2] [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#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Yoshihiro-Shimoda/treewide-Add-R-Car-S4-8-Ethernet-Switch-support/20220909-212759 base: 9a82ccda91ed2b40619cb3c10d446ae1f97bab6e config: sh-allmodconfig (https://download.01.org/0day-ci/archive/20220910/202209100156.WIC248Uh-lkp@xxxxxxxxx/config) compiler: sh4-linux-gcc (GCC) 12.1.0 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://github.com/intel-lab-lkp/linux/commit/9c5c4dd0ca6beb269dd0a6ef12c386198e193c68 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Yoshihiro-Shimoda/treewide-Add-R-Car-S4-8-Ethernet-Switch-support/20220909-212759 git checkout 9c5c4dd0ca6beb269dd0a6ef12c386198e193c68 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sh SHELL=/bin/bash M=drivers/net/ethernet/renesas If you fix the issue, kindly add following tag where applicable Reported-by: kernel test robot <lkp@xxxxxxxxx> All warnings (new ones prefixed by >>): >> drivers/net/ethernet/renesas/rswitch_serdes.c:16:6: warning: no previous prototype for 'rswitch_serdes_write32' [-Wmissing-prototypes] 16 | void rswitch_serdes_write32(void __iomem *addr, u32 offs, u32 bank, u32 data) | ^~~~~~~~~~~~~~~~~~~~~~ >> drivers/net/ethernet/renesas/rswitch_serdes.c:22:5: warning: no previous prototype for 'rswitch_serdes_read32' [-Wmissing-prototypes] 22 | u32 rswitch_serdes_read32(void __iomem *addr, u32 offs, u32 bank) | ^~~~~~~~~~~~~~~~~~~~~ vim +/rswitch_serdes_write32 +16 drivers/net/ethernet/renesas/rswitch_serdes.c 15 > 16 void rswitch_serdes_write32(void __iomem *addr, u32 offs, u32 bank, u32 data) 17 { 18 iowrite32(bank, addr + RSWITCH_SERDES_BANK_SELECT); 19 iowrite32(data, addr + offs); 20 } 21 > 22 u32 rswitch_serdes_read32(void __iomem *addr, u32 offs, u32 bank) 23 { 24 iowrite32(bank, addr + RSWITCH_SERDES_BANK_SELECT); 25 26 return ioread32(addr + offs); 27 } 28 -- 0-DAY CI Kernel Test Service https://01.org/lkp