tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   49e7e3e905e437a02782019570f70997e2da9101
commit: 805837740d0142c38ab94b2269ca28da3890ae68 [9021/11956] clk: imx: imx21: Remove clock driver
config: arm-randconfig-r022-20200929 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project de55ebe3bbc77882901ae2b9654503b7611b28f3)
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 arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=805837740d0142c38ab94b2269ca28da3890ae68
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next master
        git checkout 805837740d0142c38ab94b2269ca28da3890ae68
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm 

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

Note: the linux-next/master HEAD 49e7e3e905e437a02782019570f70997e2da9101 builds fine.
      It may have been fixed somewhere.

All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: arch/arm/mach-imx/mach-mx21ads.o: in function `mx21ads_timer_init':
>> arch/arm/mach-imx/mach-mx21ads.c:325: undefined reference to `mx21_clocks_init'
   arm-linux-gnueabi-ld: drivers/tty/tty_io.o: in function `tty_line_name':
   drivers/tty/tty_io.c:1139: undefined reference to `stpcpy'
   arm-linux-gnueabi-ld: drivers/tty/tty_io.c:1139: undefined reference to `stpcpy'
   arm-linux-gnueabi-ld: drivers/tty/tty_io.c:1139: undefined reference to `stpcpy'
   arm-linux-gnueabi-ld: drivers/scsi/scsi_transport_sas.o: in function `get_sas_device_type_names':
   drivers/scsi/scsi_transport_sas.c:131: undefined reference to `stpcpy'
   arm-linux-gnueabi-ld: drivers/scsi/scsi_transport_sas.o: in function `get_sas_linkspeed_names':
   drivers/scsi/scsi_transport_sas.c:158: undefined reference to `stpcpy'
   arm-linux-gnueabi-ld: drivers/scsi/scsi_transport_sas.o:drivers/scsi/scsi_transport_sas.c:158: more undefined references to `stpcpy' follow

vim +325 arch/arm/mach-imx/mach-mx21ads.c

6b91edde09fadde arch/arm/mach-mx2/mx21ads.c Ivo Clarysse 2009-04-15  322  
6b91edde09fadde arch/arm/mach-mx2/mx21ads.c Ivo Clarysse 2009-04-15  323  static void __init mx21ads_timer_init(void)
6b91edde09fadde arch/arm/mach-mx2/mx21ads.c Ivo Clarysse 2009-04-15  324  {
6b91edde09fadde arch/arm/mach-mx2/mx21ads.c Ivo Clarysse 2009-04-15 @325  	mx21_clocks_init(32768, 26000000);
6b91edde09fadde arch/arm/mach-mx2/mx21ads.c Ivo Clarysse 2009-04-15  326  }
6b91edde09fadde arch/arm/mach-mx2/mx21ads.c Ivo Clarysse 2009-04-15  327  

:::::: The code at line 325 was first introduced by commit
:::::: 6b91edde09fadde2657b11b454b88ae89c5b4cae MXC: mx21ads base support

:::::: TO: Ivo Clarysse <ivo.clarysse@gmail.com>
:::::: CC: Sascha Hauer <s.hauer@pengutronix.de>

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