Hi Kuninori, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on asoc/for-next] [also build test WARNING on next-20200519] [cannot apply to sound/for-next v5.7-rc6] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Kuninori-Morimoto/ASoC-add-soc-l... base: https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next config: x86_64-randconfig-r016-20200521 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 3393cc4cebf9969db94dc424b7a2b6195589c33b) 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 # 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: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): sound/soc/soc-link.c:28:5: warning: no previous prototype for function 'snd_soc_link_init' [-Wmissing-prototypes] int snd_soc_link_init(struct snd_soc_pcm_runtime *rtd) ^ sound/soc/soc-link.c:28:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int snd_soc_link_init(struct snd_soc_pcm_runtime *rtd) ^ static sound/soc/soc-link.c:38:5: warning: no previous prototype for function 'snd_soc_link_be_hw_params_fixup' [-Wmissing-prototypes] int snd_soc_link_be_hw_params_fixup(struct snd_soc_pcm_runtime *rtd, ^ sound/soc/soc-link.c:38:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int snd_soc_link_be_hw_params_fixup(struct snd_soc_pcm_runtime *rtd, ^ static sound/soc/soc-link.c:49:5: warning: no previous prototype for function 'snd_soc_link_startup' [-Wmissing-prototypes] int snd_soc_link_startup(struct snd_pcm_substream *substream) ^ sound/soc/soc-link.c:49:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int snd_soc_link_startup(struct snd_pcm_substream *substream) ^ static sound/soc/soc-link.c:61:6: warning: no previous prototype for function 'snd_soc_link_shutdown' [-Wmissing-prototypes] void snd_soc_link_shutdown(struct snd_pcm_substream *substream) ^ sound/soc/soc-link.c:61:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void snd_soc_link_shutdown(struct snd_pcm_substream *substream) ^ static sound/soc/soc-link.c:70:5: warning: no previous prototype for function 'snd_soc_link_prepare' [-Wmissing-prototypes] int snd_soc_link_prepare(struct snd_pcm_substream *substream) ^ sound/soc/soc-link.c:70:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int snd_soc_link_prepare(struct snd_pcm_substream *substream) ^ static sound/soc/soc-link.c:82:5: warning: no previous prototype for function 'snd_soc_link_hw_params' [-Wmissing-prototypes] int snd_soc_link_hw_params(struct snd_pcm_substream *substream, ^ sound/soc/soc-link.c:82:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int snd_soc_link_hw_params(struct snd_pcm_substream *substream, ^ static sound/soc/soc-link.c:95:6: warning: no previous prototype for function 'snd_soc_link_hw_free' [-Wmissing-prototypes] void snd_soc_link_hw_free(struct snd_pcm_substream *substream) ^ sound/soc/soc-link.c:95:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void snd_soc_link_hw_free(struct snd_pcm_substream *substream) ^ static sound/soc/soc-link.c:104:5: warning: no previous prototype for function 'snd_soc_link_trigger' [-Wmissing-prototypes] int snd_soc_link_trigger(struct snd_pcm_substream *substream, int cmd) ^ sound/soc/soc-link.c:104:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int snd_soc_link_trigger(struct snd_pcm_substream *substream, int cmd) ^ static sound/soc/soc-link.c:116:5: warning: no previous prototype for function 'snd_soc_link_compr_startup' [-Wmissing-prototypes] int snd_soc_link_compr_startup(struct snd_compr_stream *cstream) ^ sound/soc/soc-link.c:116:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int snd_soc_link_compr_startup(struct snd_compr_stream *cstream) ^ static void snd_soc_link_compr_shutdown(struct snd_compr_stream *cstream) ^ sound/soc/soc-link.c:129:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void snd_soc_link_compr_shutdown(struct snd_compr_stream *cstream) ^ static 10 warnings generated. vim +/snd_soc_link_compr_shutdown +129 sound/soc/soc-link.c 128 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org