Hi Tristram, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: bb5baaa9238ecf8f13b112232c7bbe0d3d598ee8 commit: 20e03777d70923fe7eae0d7f043ef9488393ab95 net: dsa: microchip: add KSZ9477 I2C driver date: 11 months ago config: x86_64-randconfig-r032-20200812 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 4f2ad15db535873dda9bfe248a2771023b64a43c) 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 git checkout 20e03777d70923fe7eae0d7f043ef9488393ab95 # 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 warnings (new ones prefixed by >>): ^ include/linux/jhash.h:95:2: note: insert '__attribute__((fallthrough));' to silence this warning case 6: b += (u32)k[5]<<8; /* fall through */ ^ __attribute__((fallthrough)); include/linux/jhash.h:95:2: note: insert 'break;' to avoid fall-through case 6: b += (u32)k[5]<<8; /* fall through */ ^ break; include/linux/jhash.h:96:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 5: b += k[4]; /* fall through */ ^ include/linux/jhash.h:96:2: note: insert '__attribute__((fallthrough));' to silence this warning case 5: b += k[4]; /* fall through */ ^ __attribute__((fallthrough)); include/linux/jhash.h:96:2: note: insert 'break;' to avoid fall-through case 5: b += k[4]; /* fall through */ ^ break; include/linux/jhash.h:97:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 4: a += (u32)k[3]<<24; /* fall through */ ^ include/linux/jhash.h:97:2: note: insert '__attribute__((fallthrough));' to silence this warning case 4: a += (u32)k[3]<<24; /* fall through */ ^ __attribute__((fallthrough)); include/linux/jhash.h:97:2: note: insert 'break;' to avoid fall-through case 4: a += (u32)k[3]<<24; /* fall through */ ^ break; include/linux/jhash.h:98:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 3: a += (u32)k[2]<<16; /* fall through */ ^ include/linux/jhash.h:98:2: note: insert '__attribute__((fallthrough));' to silence this warning case 3: a += (u32)k[2]<<16; /* fall through */ ^ __attribute__((fallthrough)); include/linux/jhash.h:98:2: note: insert 'break;' to avoid fall-through case 3: a += (u32)k[2]<<16; /* fall through */ ^ break; include/linux/jhash.h:99:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 2: a += (u32)k[1]<<8; /* fall through */ ^ include/linux/jhash.h:99:2: note: insert '__attribute__((fallthrough));' to silence this warning case 2: a += (u32)k[1]<<8; /* fall through */ ^ __attribute__((fallthrough)); include/linux/jhash.h:99:2: note: insert 'break;' to avoid fall-through case 2: a += (u32)k[1]<<8; /* fall through */ ^ break; include/linux/jhash.h:100:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 1: a += k[0]; ^ include/linux/jhash.h:100:2: note: insert '__attribute__((fallthrough));' to silence this warning case 1: a += k[0]; ^ __attribute__((fallthrough)); include/linux/jhash.h:100:2: note: insert 'break;' to avoid fall-through case 1: a += k[0]; ^ break; include/linux/jhash.h:102:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 0: /* Nothing left to add */ ^ include/linux/jhash.h:102:2: note: insert 'break;' to avoid fall-through case 0: /* Nothing left to add */ ^ break; include/linux/jhash.h:136:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 2: b += k[1]; /* fall through */ ^ include/linux/jhash.h:136:2: note: insert '__attribute__((fallthrough));' to silence this warning case 2: b += k[1]; /* fall through */ ^ __attribute__((fallthrough)); include/linux/jhash.h:136:2: note: insert 'break;' to avoid fall-through case 2: b += k[1]; /* fall through */ ^ break; include/linux/jhash.h:137:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 1: a += k[0]; ^ include/linux/jhash.h:137:2: note: insert '__attribute__((fallthrough));' to silence this warning case 1: a += k[0]; ^ __attribute__((fallthrough)); include/linux/jhash.h:137:2: note: insert 'break;' to avoid fall-through case 1: a += k[0]; ^ break; include/linux/jhash.h:139:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] case 0: /* Nothing left to add */ ^ include/linux/jhash.h:139:2: note: insert 'break;' to avoid fall-through case 0: /* Nothing left to add */ ^ break; static const struct of_device_id ksz9477_dt_ids[] = { ^ 37 warnings generated. vim +/ksz9477_dt_ids +77 drivers/net/dsa/microchip/ksz9477_i2c.c 76 78 { .compatible = "microchip,ksz9477" }, 79 { .compatible = "microchip,ksz9897" }, 80 {}, 81 }; 82 MODULE_DEVICE_TABLE(of, ksz9477_dt_ids); 83 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org