Hi Ben, I love your patch! Yet something to improve: [auto build test ERROR on 53989fad1286e652ea3655ae3367ba698da8d2ff] url: https://github.com/0day-ci/linux/commits/Ben-Widawsky/Add-drivers-for-CXL... base: 53989fad1286e652ea3655ae3367ba698da8d2ff config: arm-randconfig-r034-20211119 (attached as .config) 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://github.com/0day-ci/linux/commit/8ff43502e84dd4fa1296a131cb0cc8214... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Ben-Widawsky/Add-drivers-for-CXL-ports-and-mem-devices/20211120-080513 git checkout 8ff43502e84dd4fa1296a131cb0cc82146389db4 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=arm If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): return ioread64_hi_lo(hdm_decoder + ^ drivers/cxl/port.c:191:11: error: implicit declaration of function 'ioread64_hi_lo' [-Werror,-Wimplicit-function-declaration] base = ioread64_hi_lo(decoderN(BASE_LOW_OFFSET, i)); ^ 2 errors generated. vim +/ioread64_hi_lo +105 drivers/cxl/port.c 97 98 static u64 get_decoder_size(void __iomem *hdm_decoder, int n) 99 { 100 u32 ctrl = readl(hdm_decoder + CXL_HDM_DECODER0_CTRL_OFFSET(n)); 101 102 if (ctrl & CXL_HDM_DECODER0_CTRL_COMMITTED) 103 return 0; 104 106 CXL_HDM_DECODER0_SIZE_LOW_OFFSET(n)); 107 } 108 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org