Hi Mason,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on spi/for-next]
[also build test WARNING on v5.4-rc7]
[cannot apply to next-20191115]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Mason-Yang/mtd-spi-nor-Add-support-for-Octal-8D-8D-8D-mode/20191115-170233
base:   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next
config: nds32-allyesconfig (attached as .config)
compiler: nds32le-linux-gcc (GCC) 8.1.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=8.1.0 make.cross ARCH=nds32 

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

All warnings (new ones prefixed by >>):

   drivers/mtd/spi-nor/spi-nor.c: In function 'erase_chip':
>> drivers/mtd/spi-nor/spi-nor.c:1001:25: warning: unsigned conversion from 'int' to 'u8' {aka 'unsigned char'} changes value from '-200' to '56' [-Woverflow]
        op.cmd.ext_opcode = ~SPINOR_OP_CHIP_ERASE;
                            ^
   At top level:
   drivers/mtd/spi-nor/spi-nor.c:621:12: warning: 'write_cr2' defined but not used [-Wunused-function]
    static int write_cr2(struct spi_nor *nor, u32 addr, u8 val)
               ^~~~~~~~~

vim +1001 drivers/mtd/spi-nor/spi-nor.c

   976	
   977	/*
   978	 * Erase the whole flash memory
   979	 *
   980	 * Returns 0 if successful, non-zero otherwise.
   981	 */
   982	static int erase_chip(struct spi_nor *nor)
   983	{
   984		dev_dbg(nor->dev, " %lldKiB\n", (long long)(nor->mtd.size >> 10));
   985	
   986		if (nor->spimem) {
   987			struct spi_mem_op op =
   988				SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_CHIP_ERASE, 1),
   989					   SPI_MEM_OP_NO_ADDR,
   990					   SPI_MEM_OP_NO_DUMMY,
   991					   SPI_MEM_OP_NO_DATA);
   992	
   993			if (spi_nor_protocol_is_8_8_8(nor->write_proto)) {
   994				op.cmd.buswidth = 8;
   995				op.cmd.nbytes = 2;
   996	
   997				if (spi_nor_protocol_is_8D_8D_8D(nor->write_proto))
   998					op.cmd.dtr = true;
   999	
  1000				if (nor->ext_cmd_mode == EXT_CMD_IS_INVERSE)
> 1001					op.cmd.ext_opcode = ~SPINOR_OP_CHIP_ERASE;
  1002				else
  1003					op.cmd.ext_opcode = SPINOR_OP_CHIP_ERASE;
  1004			}
  1005	
  1006			return spi_mem_exec_op(nor->spimem, &op);
  1007		}
  1008	
  1009		return nor->write_reg(nor, SPINOR_OP_CHIP_ERASE, NULL, 0);
  1010	}
  1011	

---
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