Hi Dan,

I love your patch! Yet something to improve:

[auto build test ERROR on a38fd8748464831584a19438cbb3082b5a2dab15]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/CXL-Port-Enumeration/20210325-053311
base:   a38fd8748464831584a19438cbb3082b5a2dab15
config: arc-randconfig-r014-20210325 (attached as .config)
compiler: arceb-elf-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/efa27967ffcd67a6109c23987e76b9ed2e97ae27
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Dan-Williams/CXL-Port-Enumeration/20210325-053311
        git checkout efa27967ffcd67a6109c23987e76b9ed2e97ae27
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arc 

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 >>):

   drivers/cxl/core.c: In function 'cxl_setup_device_regs':
>> drivers/cxl/core.c:27:14: error: implicit declaration of function 'readq'; did you mean 'readb'? [-Werror=implicit-function-declaration]
      27 |  cap_array = readq(base + CXLDEV_CAP_ARRAY_OFFSET);
         |              ^~~~~
         |              readb
   cc1: some warnings being treated as errors


vim +27 drivers/cxl/core.c

     6	
     7	/**
     8	 * DOC: cxl core
     9	 *
    10	 * The CXL core provides a sysfs hierarchy for control devices and a rendezvous
    11	 * point for cross-device interleave coordination through cxl ports.
    12	 */
    13	
    14	/*
    15	 * cxl_setup_device_regs() - Detect CXL Device register blocks
    16	 * @dev: Host device of the @base mapping
    17	 * @base: mapping of CXL 2.0 8.2.8 CXL Device Register Interface
    18	 */
    19	void cxl_setup_device_regs(struct device *dev, void __iomem *base,
    20				   struct cxl_device_regs *regs)
    21	{
    22		int cap, cap_count;
    23		u64 cap_array;
    24	
    25		*regs = (struct cxl_device_regs) { 0 };
    26	
  > 27		cap_array = readq(base + CXLDEV_CAP_ARRAY_OFFSET);
    28		if (FIELD_GET(CXLDEV_CAP_ARRAY_ID_MASK, cap_array) !=
    29		    CXLDEV_CAP_ARRAY_CAP_ID)
    30			return;
    31	
    32		cap_count = FIELD_GET(CXLDEV_CAP_ARRAY_COUNT_MASK, cap_array);
    33	
    34		for (cap = 1; cap <= cap_count; cap++) {
    35			void __iomem *register_block;
    36			u32 offset;
    37			u16 cap_id;
    38	
    39			cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK,
    40					   readl(base + cap * 0x10));
    41			offset = readl(base + cap * 0x10 + 0x4);
    42			register_block = base + offset;
    43	
    44			switch (cap_id) {
    45			case CXLDEV_CAP_CAP_ID_DEVICE_STATUS:
    46				dev_dbg(dev, "found Status capability (0x%x)\n", offset);
    47				regs->status = register_block;
    48				break;
    49			case CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX:
    50				dev_dbg(dev, "found Mailbox capability (0x%x)\n", offset);
    51				regs->mbox = register_block;
    52				break;
    53			case CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX:
    54				dev_dbg(dev, "found Secondary Mailbox capability (0x%x)\n", offset);
    55				break;
    56			case CXLDEV_CAP_CAP_ID_MEMDEV:
    57				dev_dbg(dev, "found Memory Device capability (0x%x)\n", offset);
    58				regs->memdev = register_block;
    59				break;
    60			default:
    61				dev_dbg(dev, "Unknown cap ID: %d (0x%x)\n", cap_id, offset);
    62				break;
    63			}
    64		}
    65	}
    66	EXPORT_SYMBOL_GPL(cxl_setup_device_regs);
    67	

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