[cip:linux-4.4.y-st-rc 1077/2707] drivers/spi/spi-fsl-cpm.c:137:17: warning: comparison between signed and unsigned integer expressions

[cip:linux-4.4.y-st-rc 1077/2707] drivers/spi/spi-fsl-cpm.c:137:17: warning: comparison between signed and unsigned integer expressions

[kernel test robot]

Hi Christophe,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/cip/linux-cip.git linux-4.4.y-st-rc
head:   aea4aaf86b7212944b7bf66d6becb8c7bb51093e
commit: 8cfd8c7919b40a5c5c5646f4eefaa8b46090b610 [1077/2707] spi: fsl-cpm: Use 16 bit mode for large transfers with even size
config: powerpc-randconfig-003-20241003 (https://download.01.org/0day-ci/archive/20241004/202410040044.rcbPKuWD-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 7.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241004/202410040044.rcbPKuWD-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410040044.rcbPKuWD-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/scatterlist.h:7:0,
                    from include/linux/dma-mapping.h:10,
                    from drivers/spi/spi-fsl-cpm.c:20:
   include/linux/mm.h: In function 'is_vmalloc_addr':
   include/linux/mm.h:386:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     return addr >= VMALLOC_START && addr < VMALLOC_END;
                 ^~
   drivers/spi/spi-fsl-cpm.c: In function 'fsl_spi_cpm_bufs':
>> drivers/spi/spi-fsl-cpm.c:137:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for (i = 0; i < t->len >> 1; i++)
                    ^
   drivers/spi/spi-fsl-cpm.c: In function 'fsl_spi_cpm_bufs_complete':
   drivers/spi/spi-fsl-cpm.c:200:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for (i = 0; i < t->len; i += 2)
                    ^


vim +137 drivers/spi/spi-fsl-cpm.c

   104	
   105	int fsl_spi_cpm_bufs(struct mpc8xxx_spi *mspi,
   106			     struct spi_transfer *t, bool is_dma_mapped)
   107	{
   108		struct device *dev = mspi->dev;
   109		struct fsl_spi_reg *reg_base = mspi->reg_base;
   110	
   111		if (is_dma_mapped) {
   112			mspi->map_tx_dma = 0;
   113			mspi->map_rx_dma = 0;
   114		} else {
   115			mspi->map_tx_dma = 1;
   116			mspi->map_rx_dma = 1;
   117		}
   118	
   119		if (!t->tx_buf) {
   120			mspi->tx_dma = mspi->dma_dummy_tx;
   121			mspi->map_tx_dma = 0;
   122		}
   123	
   124		if (!t->rx_buf) {
   125			mspi->rx_dma = mspi->dma_dummy_rx;
   126			mspi->map_rx_dma = 0;
   127		}
   128		if (t->bits_per_word == 16 && t->tx_buf) {
   129			const u16 *src = t->tx_buf;
   130			u16 *dst;
   131			int i;
   132	
   133			dst = kmalloc(t->len, GFP_KERNEL);
   134			if (!dst)
   135				return -ENOMEM;
   136	
 > 137			for (i = 0; i < t->len >> 1; i++)
   138				dst[i] = cpu_to_le16p(src + i);
   139	
   140			mspi->tx = dst;
   141			mspi->map_tx_dma = 1;
   142		}
   143	
   144		if (mspi->map_tx_dma) {
   145			void *nonconst_tx = (void *)mspi->tx; /* shut up gcc */
   146	
   147			mspi->tx_dma = dma_map_single(dev, nonconst_tx, t->len,
   148						      DMA_TO_DEVICE);
   149			if (dma_mapping_error(dev, mspi->tx_dma)) {
   150				dev_err(dev, "unable to map tx dma\n");
   151				return -ENOMEM;
   152			}
   153		} else if (t->tx_buf) {
   154			mspi->tx_dma = t->tx_dma;
   155		}
   156	
   157		if (mspi->map_rx_dma) {
   158			mspi->rx_dma = dma_map_single(dev, mspi->rx, t->len,
   159						      DMA_FROM_DEVICE);
   160			if (dma_mapping_error(dev, mspi->rx_dma)) {
   161				dev_err(dev, "unable to map rx dma\n");
   162				goto err_rx_dma;
   163			}
   164		} else if (t->rx_buf) {
   165			mspi->rx_dma = t->rx_dma;
   166		}
   167	
   168		/* enable rx ints */
   169		mpc8xxx_spi_write_reg(&reg_base->mask, SPIE_RXB);
   170	
   171		mspi->xfer_in_progress = t;
   172		mspi->count = t->len;
   173	
   174		/* start CPM transfers */
   175		fsl_spi_cpm_bufs_start(mspi);
   176	
   177		return 0;
   178	
   179	err_rx_dma:
   180		if (mspi->map_tx_dma)
   181			dma_unmap_single(dev, mspi->tx_dma, t->len, DMA_TO_DEVICE);
   182		return -ENOMEM;
   183	}
   184	EXPORT_SYMBOL_GPL(fsl_spi_cpm_bufs);
   185	

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https://github.com/intel/lkp-tests/wiki