Re: [PATCH] wifi: mt76: mmio_(read|write)_copy byte swap when on Big Endian

[Caleb James DeLisle <cjd@cjdns.fr>]

On 31/10/2025 02:18, kernel test robot wrote:
> Hi Caleb,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on wireless-next/main]
> [also build test WARNING on wireless/main linus/master v6.18-rc3 next-20251030]
> [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#_base_tree_information]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/Caleb-James-DeLisle/wifi-mt76-mmio_-read-write-_copy-byte-swap-when-on-Big-Endian/20251028-012349
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git main
> patch link:    https://lore.kernel.org/r/20251027171759.1484844-1-cjd%40cjdns.fr
> patch subject: [PATCH] wifi: mt76: mmio_(read|write)_copy byte swap when on Big Endian
> config: i386-randconfig-061-20251031 (https://download.01.org/0day-ci/archive/20251031/202510310816.kyDHJNiS-lkp@intel.com/config)
> compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251031/202510310816.kyDHJNiS-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/202510310816.kyDHJNiS-lkp@intel.com/
>
> sparse warnings: (new ones prefixed by >>)
>>> drivers/net/wireless/mediatek/mt76/mmio.c:41:24: sparse: sparse: cast from restricted __le32
>>> drivers/net/wireless/mediatek/mt76/mmio.c:41:24: sparse: sparse: incorrect type in argument 1 (different base types) @@     expected unsigned int val @@     got restricted __le32 [usertype] @@


This should not be an issue in PATCH v2 because it no longer uses a 
temporary variable.

Thanks,

Caleb


>     drivers/net/wireless/mediatek/mt76/mmio.c:41:24: sparse:     expected unsigned int val
>     drivers/net/wireless/mediatek/mt76/mmio.c:41:24: sparse:     got restricted __le32 [usertype]
>>> drivers/net/wireless/mediatek/mt76/mmio.c:63:23: sparse: sparse: cast to restricted __le32
> vim +41 drivers/net/wireless/mediatek/mt76/mmio.c
>
>      32	
>      33	static void mt76_mmio_write_copy_portable(void __iomem *dst,
>      34						  const u8 *src, int len)
>      35	{
>      36		__le32 val;
>      37		int i = 0;
>      38	
>      39		for (i = 0; i < ALIGN(len, 4); i += 4) {
>      40			memcpy(&val, src + i, sizeof(val));
>    > 41			writel(cpu_to_le32(val), dst + i);
>      42		}
>      43	}
>      44	
>      45	static void mt76_mmio_write_copy(struct mt76_dev *dev, u32 offset,
>      46					 const void *data, int len)
>      47	{
>      48		if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) {
>      49			mt76_mmio_write_copy_portable(dev->mmio.regs + offset, data,
>      50						      len);
>      51			return;
>      52		}
>      53		__iowrite32_copy(dev->mmio.regs + offset, data, DIV_ROUND_UP(len, 4));
>      54	}
>      55	
>      56	static void mt76_mmio_read_copy_portable(u8 *dst,
>      57						 const void __iomem *src, int len)
>      58	{
>      59		u32 val;
>      60		int i;
>      61	
>      62		for (i = 0; i < ALIGN(len, 4); i += 4) {
>    > 63			val = le32_to_cpu(readl(src + i));
>      64			memcpy(dst + i, &val, sizeof(val));
>      65		}
>      66	}
>      67	
>