tree: git://git.infradead.org/users/hch/dma-mapping for-next head: 2a410d09417b5344ab1f3cf001ac73a1daf8dcce commit: 7bc5c428a660d4d1bc95ba54bf4cb6bccf8c3029 [16/64] dma-direct: remove __dma_to_phys config: mips-randconfig-r026-20201014 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project e7fe3c6dfede8d5781bd000741c3dea7088307a4) 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 mips cross compiling tool for clang build # apt-get install binutils-mips-linux-gnu git remote add hch-dma-mapping git://git.infradead.org/users/hch/dma-mapping git fetch --no-tags hch-dma-mapping for-next git checkout 7bc5c428a660d4d1bc95ba54bf4cb6bccf8c3029 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips 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 >>): arch/mips/bmips/dma.c:43:12: warning: no previous prototype for function '__phys_to_dma' [-Wmissing-prototypes] dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t pa) ^ arch/mips/bmips/dma.c:43:1: note: declare 'static' if the function is not intended to be used outside of this translation unit dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t pa) ^ static phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dma_addr) ^ arch/mips/bmips/dma.c:55:1: note: declare 'static' if the function is not intended to be used outside of this translation unit phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dma_addr) ^ static arch/mips/bmips/dma.c:67:6: warning: no previous prototype for function 'arch_sync_dma_for_cpu_all' [-Wmissing-prototypes] void arch_sync_dma_for_cpu_all(void) ^ arch/mips/bmips/dma.c:67:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void arch_sync_dma_for_cpu_all(void) ^ static 3 warnings generated. vim +/dma_to_phys +55 arch/mips/bmips/dma.c 54 56 { 57 struct bmips_dma_range *r; 58 59 for (r = bmips_dma_ranges; r && r->size; r++) { 60 if (dma_addr >= r->parent_addr && 61 dma_addr < (r->parent_addr + r->size)) 62 return dma_addr - r->parent_addr + r->child_addr; 63 } 64 return dma_addr; 65 } 66 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org