[linux-stable-rc:linux-4.19.y 7073/9999] drivers/tty/serial/stm32-usart.c:602:14: warning: no previous prototype for function 'stm32_get_databits'

[linux-stable-rc:linux-4.19.y 7073/9999] drivers/tty/serial/stm32-usart.c:602:14: warning: no previous prototype for function 'stm32_get_databits'

[kernel test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.19.y
head:   e864f43593ccf9180c61738abdf1c1dde091367d
commit: 144fdb20e5c8fb4f14a75225ff8de885c78271f5 [7073/9999] serial: stm32: fix word length configuration
config: x86_64-randconfig-a004-20200906 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 781a43840863b85603a710857691a9b5032b0c27)
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
        git checkout 144fdb20e5c8fb4f14a75225ff8de885c78271f5
        # 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: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/tty/serial/stm32-usart.c:602:14: warning: no previous prototype for function 'stm32_get_databits' [-Wmissing-prototypes]
   unsigned int stm32_get_databits(struct ktermios *termios)
                ^
   drivers/tty/serial/stm32-usart.c:602:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   unsigned int stm32_get_databits(struct ktermios *termios)
   ^
   static 
   1 warning generated.

# https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?id=144fdb20e5c8fb4f14a75225ff8de885c78271f5
git remote add linux-stable-rc https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
git fetch --no-tags linux-stable-rc linux-4.19.y
git checkout 144fdb20e5c8fb4f14a75225ff8de885c78271f5
vim +/stm32_get_databits +602 drivers/tty/serial/stm32-usart.c

   601	
 > 602	unsigned int stm32_get_databits(struct ktermios *termios)
   603	{
   604		unsigned int bits;
   605	
   606		tcflag_t cflag = termios->c_cflag;
   607	
   608		switch (cflag & CSIZE) {
   609		/*
   610		 * CSIZE settings are not necessarily supported in hardware.
   611		 * CSIZE unsupported configurations are handled here to set word length
   612		 * to 8 bits word as default configuration and to print debug message.
   613		 */
   614		case CS5:
   615			bits = 5;
   616			break;
   617		case CS6:
   618			bits = 6;
   619			break;
   620		case CS7:
   621			bits = 7;
   622			break;
   623		/* default including CS8 */
   624		default:
   625			bits = 8;
   626			break;
   627		}
   628	
   629		return bits;
   630	}
   631	

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

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