Hi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url:    https://github.com/0day-ci/linux/commits/luizluca-gmail-com/net-dsa-realtek-MDIO-interface-and-RTL8367S/20211217-041735
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 0f473bb6ed2d0b8533a079ee133f625f83de5315
config: arc-allyesconfig (https://download.01.org/0day-ci/archive/20211217/202112171150.GzuAOv0N-lkp@intel.com/config)
compiler: arceb-elf-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/15bfe75ad3669cdcef7bfab281d7744c226fc503
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review luizluca-gmail-com/net-dsa-realtek-MDIO-interface-and-RTL8367S/20211217-041735
        git checkout 15bfe75ad3669cdcef7bfab281d7744c226fc503
        # 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=arc SHELL=/bin/bash drivers/net/dsa/realtek/

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/net/dsa/realtek/realtek-mdio.c:54:5: warning: no previous prototype for 'realtek_mdio_read_reg' [-Wmissing-prototypes]
      54 | int realtek_mdio_read_reg(struct realtek_priv *priv, u32 addr, u32 *data)
         |     ^~~~~~~~~~~~~~~~~~~~~


vim +/realtek_mdio_read_reg +54 drivers/net/dsa/realtek/realtek-mdio.c

    53	
  > 54	int realtek_mdio_read_reg(struct realtek_priv *priv, u32 addr, u32 *data)
    55	{
    56	        u32 phy_id = priv->phy_id;
    57		struct mii_bus *bus = priv->bus;
    58	
    59	        BUG_ON(in_interrupt());
    60	
    61	        mutex_lock(&bus->mdio_lock);
    62	        /* Write Start command to register 29 */
    63	        bus->write(bus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
    64	
    65	        /* Write address control code to register 31 */
    66	        bus->write(bus, phy_id, MDC_MDIO_CTRL0_REG, MDC_MDIO_ADDR_OP);
    67	
    68	        /* Write Start command to register 29 */
    69	        bus->write(bus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
    70	
    71	        /* Write address to register 23 */
    72	        bus->write(bus, phy_id, MDC_MDIO_ADDRESS_REG, addr);
    73	
    74	        /* Write Start command to register 29 */
    75	        bus->write(bus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
    76	
    77	        /* Write read control code to register 21 */
    78	        bus->write(bus, phy_id, MDC_MDIO_CTRL1_REG, MDC_MDIO_READ_OP);
    79	
    80	        /* Write Start command to register 29 */
    81	        bus->write(bus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
    82	
    83	        /* Read data from register 25 */
    84	        *data = bus->read(bus, phy_id, MDC_MDIO_DATA_READ_REG);
    85	
    86	        mutex_unlock(&bus->mdio_lock);
    87	
    88	        return 0;
    89	}
    90	

---
0-DAY CI Kernel Test Service, Intel Corporation
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