Hi Nicholas,

I love your patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[also build test ERROR on v5.16-rc1 next-20211115]
[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/Nicholas-Piggin/powerpc-64s-Get-LPID-bit-width-from-device-tree/20211110-160038
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc64-randconfig-c024-20211115 (attached as .config)
compiler: powerpc64-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/b8fe7181506bf3011295456a9ee471ddf49d694d
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Nicholas-Piggin/powerpc-64s-Get-LPID-bit-width-from-device-tree/20211110-160038
        git checkout b8fe7181506bf3011295456a9ee471ddf49d694d
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=powerpc 

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 >>):

   arch/powerpc/mm/init_64.c: In function 'mmu_early_init_devtree':
>> arch/powerpc/mm/init_64.c:472:13: error: variable 'rc' set but not used [-Werror=unused-but-set-variable]
     472 |         int rc;
         |             ^~
   cc1: all warnings being treated as errors


vim +/rc +472 arch/powerpc/mm/init_64.c

   469	
   470	void __init mmu_early_init_devtree(void)
   471	{
 > 472		int rc;

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