Hi Christoph,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   e71ba9452f0b5b2e8dc8aa5445198cd9214a6a62
commit: 7bc5c428a660d4d1bc95ba54bf4cb6bccf8c3029 dma-direct: remove __dma_to_phys
date:   4 months ago
config: mips-randconfig-r021-20210107 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 5c951623bc8965fa1e89660f2f5f4a2944e4981a)
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
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7bc5c428a660d4d1bc95ba54bf4cb6bccf8c3029
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        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@intel.com>

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 
>> arch/mips/bmips/dma.c:55:13: warning: no previous prototype for function 'dma_to_phys' [-Wmissing-prototypes]
   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

    42	
  > 43	dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t pa)
    44	{
    45		struct bmips_dma_range *r;
    46	
    47		for (r = bmips_dma_ranges; r && r->size; r++) {
    48			if (pa >= r->child_addr &&
    49			    pa < (r->child_addr + r->size))
    50				return pa - r->child_addr + r->parent_addr;
    51		}
    52		return pa;
    53	}
    54	
  > 55	phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dma_addr)
    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
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