Hi Oliver, FYI, the error/warning still remains. tree: https://github.com/Freescale/linux-fslc 5.4-2.3.x-imx head: 4efcf5cb62af1dae546bc1022b4edf6dedb6c983 commit: 53ecae250dd9e334787ede9eb40e0555b7fd0c00 [15436/19460] MLK-24911-1: soc: imx: Add support to get iMX8mp LDO trim fuse value config: arm64-randconfig-r014-20210621 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project e1adf90826a57b674eee79b071fb46c1f5683cd0) 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 arm64 cross compiling tool for clang build # apt-get install binutils-aarch64-linux-gnu # https://github.com/Freescale/linux-fslc/commit/53ecae250dd9e334787ede9eb4... git remote add freescale-fslc https://github.com/Freescale/linux-fslc git fetch --no-tags freescale-fslc 5.4-2.3.x-imx git checkout 53ecae250dd9e334787ede9eb40e0555b7fd0c00 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 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 >>): In file included from drivers/soc/imx/soc-imx8.c:8: In file included from include/linux/io.h:13: In file included from arch/arm64/include/asm/io.h:16: In file included from arch/arm64/include/asm/pgtable.h:14: arch/arm64/include/asm/tlbflush.h:200:16: warning: variable 'mask' set but not used [-Wunused-but-set-variable] unsigned long mask = (1 << 20) - 1; ^ drivers/soc/imx/soc-imx8.c:324:5: warning: no previous prototype for function 'check_m4_enabled' [-Wmissing-prototypes] int check_m4_enabled(void) ^ drivers/soc/imx/soc-imx8.c:324:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int check_m4_enabled(void) ^ static int imx8mp_get_ldo_trim(int ldo) ^ drivers/soc/imx/soc-imx8.c:339:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int imx8mp_get_ldo_trim(int ldo) ^ static 3 warnings generated. vim +/imx8mp_get_ldo_trim +339 drivers/soc/imx/soc-imx8.c 338 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org