arch/mips/boot/compressed/uart-alchemy.c:4:6: warning: no previous prototype for 'putc'

[kernel test robot <lkp@intel.com>]

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Hi Thomas,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   9ccce092fc64d19504fa54de4fd659e279cc92e7
commit: 396c7d94c3bbe07ae00c9f694a5c731878843038 MIPS: alchemy: Fix build breakage, if TOUCHSCREEN_WM97XX is disabled
date:   7 months ago
config: mips-randconfig-r023-20210503 (attached as .config)
compiler: mipsel-linux-gcc (GCC) 9.3.0
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
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=396c7d94c3bbe07ae00c9f694a5c731878843038
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 396c7d94c3bbe07ae00c9f694a5c731878843038
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 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/boot/compressed/uart-alchemy.c:4:6: warning: no previous prototype for 'putc' [-Wmissing-prototypes]
       4 | void putc(char c)
         |      ^~~~


vim +/putc +4 arch/mips/boot/compressed/uart-alchemy.c

aae7e8da806e15 Manuel Lauss 2010-01-13  3  
aae7e8da806e15 Manuel Lauss 2010-01-13 @4  void putc(char c)

:::::: The code at line 4 was first introduced by commit
:::::: aae7e8da806e1536fdee0632a40aaaeed97a2f1b MIPS: Alchemy: debug output for compressed kernels

:::::: TO: Manuel Lauss <manuel.lauss@googlemail.com>
:::::: CC: Ralf Baechle <ralf@linux-mips.org>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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