Hi Sander,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on pavel-linux-leds/for-next]
[also build test ERROR on lee-mfd/for-mfd-next pinctrl/devel v5.13-rc1]
[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/Sander-Vanheule/RTL8231-GPIO-expander-support/20210511-202618
base:   git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds.git for-next
config: microblaze-randconfig-r023-20210512 (attached as .config)
compiler: microblaze-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://github.com/0day-ci/linux/commit/e031cc2da2c2948230bacd1ca56cfe9990e1aefd
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Sander-Vanheule/RTL8231-GPIO-expander-support/20210511-202618
        git checkout e031cc2da2c2948230bacd1ca56cfe9990e1aefd
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=microblaze 

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

All errors (new ones prefixed by >>):

   microblaze-linux-ld: drivers/mfd/rtl8231.o: in function `rtl8231_mdio_reg_write':
>> (.text+0x50): undefined reference to `mdiobus_write'
   microblaze-linux-ld: drivers/mfd/rtl8231.o: in function `rtl8231_mdio_reg_read':
>> (.text+0x80): undefined reference to `mdiobus_read'
   microblaze-linux-ld: drivers/mfd/rtl8231.o: in function `mdio_module_init':
>> (.init.text+0x10): undefined reference to `mdio_driver_register'
   microblaze-linux-ld: drivers/mfd/rtl8231.o: in function `mdio_module_exit':
>> (.exit.text+0x10): undefined reference to `mdio_driver_unregister'

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