[l1k:bcm2835_spi_clkcache 1/1] drivers/spi/spi-bcm2835.c:1048:1: warning: no previous prototype for 'bcm2835_spi_set_clk'

[kernel test robot]

tree:   https://github.com/l1k/linux bcm2835_spi_clkcache
head:   c26ae7b1acc28bc6d97707230886c6fe9ece7d15
commit: c26ae7b1acc28bc6d97707230886c6fe9ece7d15 [1/1] spi: bcm2835: Avoid unnecessary recalculation of CLK register
config: arm64-randconfig-r022-20210912 (attached as .config)
compiler: aarch64-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/l1k/linux/commit/c26ae7b1acc28bc6d97707230886c6fe9ece7d15
        git remote add l1k https://github.com/l1k/linux
        git fetch --no-tags l1k bcm2835_spi_clkcache
        git checkout c26ae7b1acc28bc6d97707230886c6fe9ece7d15
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=arm64 

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

All warnings (new ones prefixed by >>):

   drivers/spi/spi-bcm2835.c:1048:1: error: return type defaults to 'int' [-Werror=return-type]
    1048 | bcm2835_spi_set_clk(struct bcm2835_spi *bs, struct spi_transfer *tfr)
         | ^~~~~~~~~~~~~~~~~~~
>> drivers/spi/spi-bcm2835.c:1048:1: warning: no previous prototype for 'bcm2835_spi_set_clk' [-Wmissing-prototypes]
   drivers/spi/spi-bcm2835.c: In function 'bcm2835_spi_set_clk':
   drivers/spi/spi-bcm2835.c:1070:1: error: control reaches end of non-void function [-Werror=return-type]
    1070 | }
         | ^
   cc1: some warnings being treated as errors


vim +/bcm2835_spi_set_clk +1048 drivers/spi/spi-bcm2835.c

  1047	
> 1048	bcm2835_spi_set_clk(struct bcm2835_spi *bs, struct spi_transfer *tfr)
  1049	{
  1050		unsigned long spi_hz = bs->speed_hz = tfr->speed_hz;
  1051		unsigned long cdiv;
  1052	
  1053		if (spi_hz >= bs->clk_hz / 2) {
  1054			cdiv = 2; /* clk_hz/2 is the fastest we can go */
  1055		} else if (spi_hz) {
  1056			/* CDIV must be a multiple of two */
  1057			cdiv = DIV_ROUND_UP(bs->clk_hz, spi_hz);
  1058			cdiv += (cdiv % 2);
  1059	
  1060			if (cdiv >= 65536)
  1061				cdiv = 0; /* 0 is the slowest we can go */
  1062		} else {
  1063			cdiv = 0; /* 0 is the slowest we can go */
  1064		}
  1065	
  1066		tfr->effective_speed_hz = bs->effective_speed_hz =
  1067			cdiv ? (bs->clk_hz / cdiv) : (bs->clk_hz / 65536);
  1068	
  1069		bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
  1070	}
  1071	

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

Attachment: .config.gz
Description: application/gzip