Hi Hammer,

I love your patch! Perhaps something to improve:

[auto build test WARNING on tty/tty-testing]
[also build test WARNING on robh/for-next linux/master linus/master v5.16]
[cannot apply to next-20220112]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Hammer-Hsieh/Add-UART-driver-for-Suplus-SP7021-SoC/20220112-172542
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
config: mips-allyesconfig (https://download.01.org/0day-ci/archive/20220112/202201121943.u8vGs7ty-lkp(a)intel.com/config)
compiler: mips-linux-gcc (GCC) 11.2.0
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://github.com/0day-ci/linux/commit/359e5930a7804fbe8d313226cfec1ff484c16d11
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Hammer-Hsieh/Add-UART-driver-for-Suplus-SP7021-SoC/20220112-172542
        git checkout 359e5930a7804fbe8d313226cfec1ff484c16d11
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=mips SHELL=/bin/bash drivers/tty/serial/

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/sunplus-uart.c: In function 'sunplus_poll_put_char':
   drivers/tty/serial/sunplus-uart.c:430:9: error: implicit declaration of function 'wait_for_xmitr'; did you mean 'wait_on_bit'? [-Werror=implicit-function-declaration]
     430 |         wait_for_xmitr(port);
         |         ^~~~~~~~~~~~~~
         |         wait_on_bit
   drivers/tty/serial/sunplus-uart.c: At top level:
>> drivers/tty/serial/sunplus-uart.c:469:13: warning: conflicting types for 'wait_for_xmitr'; have 'void(struct uart_port *)'
     469 | static void wait_for_xmitr(struct uart_port *port)
         |             ^~~~~~~~~~~~~~
   drivers/tty/serial/sunplus-uart.c:469:13: error: static declaration of 'wait_for_xmitr' follows non-static declaration
   drivers/tty/serial/sunplus-uart.c:430:9: note: previous implicit declaration of 'wait_for_xmitr' with type 'void(struct uart_port *)'
     430 |         wait_for_xmitr(port);
         |         ^~~~~~~~~~~~~~
   drivers/tty/serial/sunplus-uart.c: In function 'sunplus_uart_probe':
   drivers/tty/serial/sunplus-uart.c:624:40: warning: cast between incompatible function types from 'int (*)(struct reset_control *)' to 'void (*)(void *)' [-Wcast-function-type]
     624 |                                        (void(*)(void *))reset_control_assert,
         |                                        ^
   cc1: some warnings being treated as errors


vim +469 drivers/tty/serial/sunplus-uart.c

   468	
 > 469	static void wait_for_xmitr(struct uart_port *port)
   470	{
   471		unsigned int val;
   472		int ret;
   473	
   474		/* Wait while FIFO is full or timeout */
   475		ret = readl_poll_timeout_atomic(port->membase + SUP_UART_LSR, val,
   476						(val & SUP_UART_LSR_TX), 1, 10000);
   477	
   478		if (ret == -ETIMEDOUT) {
   479			dev_err(port->dev, "Timeout waiting while UART TX FULL\n");
   480			return;
   481		}
   482	}
   483	

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