linux-kernel - Re: [PATCH V4] drm/ast: Swap framebuffer writes on big-endian machines

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Message-ID: <202512210011.dKKTJkNT-lkp@intel.com>
Date: Sun, 21 Dec 2025 00:31:07 +0800
From: kernel test robot <lkp@...el.com>
To: René Rebe <rene@...ctco.de>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc: oe-kbuild-all@...ts.linux.dev, Dave Airlie <airlied@...hat.com>,
	Thomas Zimmermann <tzimmermann@...e.de>
Subject: Re: [PATCH V4] drm/ast: Swap framebuffer writes on big-endian
 machines

Hi René,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on drm/drm-next drm-i915/for-linux-next drm-i915/for-linux-next-fixes drm-tip/drm-tip linus/master v6.19-rc1 next-20251219]
[cannot apply to daeinki-drm-exynos/exynos-drm-next]
[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/Ren-Rebe/drm-ast-Swap-framebuffer-writes-on-big-endian-machines/20251213-040713
base:   https://gitlab.freedesktop.org/drm/misc/kernel.git drm-misc-next
patch link:    https://lore.kernel.org/r/20251212.210504.1355099120650239629.rene%40exactco.de
patch subject: [PATCH V4] drm/ast: Swap framebuffer writes on big-endian machines
config: openrisc-randconfig-r122-20251217 (https://download.01.org/0day-ci/archive/20251221/202512210011.dKKTJkNT-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251221/202512210011.dKKTJkNT-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512210011.dKKTJkNT-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/gpu/drm/ast/ast_cursor.c:103:24: sparse: sparse: incorrect type in argument 1 (different base types) @@     expected unsigned short [usertype] val @@     got restricted __be16 const [usertype] @@
   drivers/gpu/drm/ast/ast_cursor.c:103:24: sparse:     expected unsigned short [usertype] val
   drivers/gpu/drm/ast/ast_cursor.c:103:24: sparse:     got restricted __be16 const [usertype]
>> drivers/gpu/drm/ast/ast_cursor.c:103:24: sparse: sparse: cast from restricted __be16
>> drivers/gpu/drm/ast/ast_cursor.c:103:24: sparse: sparse: cast from restricted __be16

vim +103 drivers/gpu/drm/ast/ast_cursor.c

    91	
    92	static void ast_set_cursor_image(struct ast_device *ast, const u8 *src,
    93					 unsigned int width, unsigned int height)
    94	{
    95		u8 __iomem *dst = ast_plane_vaddr(&ast->cursor_plane.base);
    96		u32 csum = ast_cursor_calculate_checksum(src, width, height);
    97	
    98		/* write pixel data */
    99	#if defined(__BIG_ENDIAN)
   100		unsigned int i;
   101	
   102		for (i = 0; i < AST_HWC_SIZE; i += 2)
 > 103			writew(swab16(*(const __be16 *)&src[i]), &dst[i]);
   104	#else
   105		memcpy_toio(dst, src, AST_HWC_SIZE);
   106	#endif
   107	
   108		/* write checksum + signature */
   109		dst += AST_HWC_SIZE;
   110		writel(csum, dst);
   111		writel(width, dst + AST_HWC_SIGNATURE_SizeX);
   112		writel(height, dst + AST_HWC_SIGNATURE_SizeY);
   113		writel(0, dst + AST_HWC_SIGNATURE_HOTSPOTX);
   114		writel(0, dst + AST_HWC_SIGNATURE_HOTSPOTY);
   115	}
   116	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki