arch/mips/boot/compressed/uart-16550.c:44:6: warning: no previous prototype for function 'putc'

[kernel test robot]

Hi YunQiang,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   32346491ddf24599decca06190ebca03ff9de7f8
commit: 31b2f3dc851c65fee288612432c4fc956f1a264e MIPS: enable both vmlinux.gz.itb and vmlinuz for generic
date:   6 months ago
config: mips-buildonly-randconfig-r003-20220711 (https://download.01.org/0day-ci/archive/20220711/202207111655.stMxhZ0j-lkp@xxxxxxxxx/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 6ce63e267aab79ca87bf63453d34dd3909ab978d)
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-mipsel-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=31b2f3dc851c65fee288612432c4fc956f1a264e
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 31b2f3dc851c65fee288612432c4fc956f1a264e
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>

Note: functions only called from assembly code should be annotated with the asmlinkage attribute
All warnings (new ones prefixed by >>):

>> arch/mips/boot/compressed/uart-16550.c:44:6: warning: no previous prototype for function 'putc' [-Wmissing-prototypes]
   void putc(char c)
        ^
   arch/mips/boot/compressed/uart-16550.c:44:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void putc(char c)
   ^
   static 
   1 warning generated.


vim +/putc +44 arch/mips/boot/compressed/uart-16550.c

1b93b3c3e94be2 Wu Zhangjin 2009-10-14  43  
1b93b3c3e94be2 Wu Zhangjin 2009-10-14 @44  void putc(char c)

:::::: The code at line 44 was first introduced by commit
:::::: 1b93b3c3e94be2605759735a89fc935ba5f58dcf MIPS: Add support for GZIP / BZIP2 / LZMA compressed kernel images

:::::: TO: Wu Zhangjin <wuzhangjin@xxxxxxxxx>
:::::: CC: Ralf Baechle <ralf@xxxxxxxxxxxxxx>

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp