Hi Bartlomiej,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   b791d1bdf9212d944d749a5c7ff6febdba241771
commit: a07a63b0e24dd1316d11427601a9f83dc955bb40 video: fbdev: controlfb: add COMPILE_TEST support
date:   8 weeks ago
config: m68k-randconfig-r025-20200612 (attached as .config)
compiler: m68k-linux-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
        git checkout a07a63b0e24dd1316d11427601a9f83dc955bb40
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k 

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 >>, old ones prefixed by <<):

drivers/video/fbdev/controlfb.c: In function 'controlfb_mmap':
>> drivers/video/fbdev/controlfb.c:326:23: error: implicit declaration of function 'pgprot_noncached' [-Werror=implicit-function-declaration]
326 |   vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
|                       ^~~~~~~~~~~~~~~~
drivers/video/fbdev/controlfb.c:326:23: error: incompatible types when assigning to type 'pgprot_t' {aka 'struct <anonymous>'} from type 'int'
drivers/video/fbdev/controlfb.c: In function 'controlfb_setcolreg':
drivers/video/fbdev/controlfb.c:373:13: warning: variable 'b' set but not used [-Wunused-but-set-variable]
373 |  __u8 r, g, b;
|             ^
drivers/video/fbdev/controlfb.c:373:10: warning: variable 'g' set but not used [-Wunused-but-set-variable]
373 |  __u8 r, g, b;
|          ^
drivers/video/fbdev/controlfb.c:373:7: warning: variable 'r' set but not used [-Wunused-but-set-variable]
373 |  __u8 r, g, b;
|       ^
drivers/video/fbdev/controlfb.c: In function 'control_set_hardware':
drivers/video/fbdev/controlfb.c:505:11: warning: variable 'cmode' set but not used [-Wunused-but-set-variable]
505 |  int   i, cmode;
|           ^~~~~
cc1: some warnings being treated as errors

vim +/pgprot_noncached +326 drivers/video/fbdev/controlfb.c

^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  303  
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  304  
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  305  /*
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  306   * Private mmap since we want to have a different caching on the framebuffer
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  307   * for controlfb.
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  308   * Note there's no locking in here; it's done in fb_mmap() in fbmem.c.
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  309   */
216d526c89d144 drivers/video/controlfb.c Christoph Hellwig      2006-01-14  310  static int controlfb_mmap(struct fb_info *info,
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  311                         struct vm_area_struct *vma)
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  312  {
47f698a9f2fc49 drivers/video/controlfb.c Tomi Valkeinen         2013-04-17  313  	unsigned long mmio_pgoff;
47f698a9f2fc49 drivers/video/controlfb.c Tomi Valkeinen         2013-04-17  314  	unsigned long start;
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  315  	u32 len;
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  316  
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  317  	start = info->fix.smem_start;
47f698a9f2fc49 drivers/video/controlfb.c Tomi Valkeinen         2013-04-17  318  	len = info->fix.smem_len;
47f698a9f2fc49 drivers/video/controlfb.c Tomi Valkeinen         2013-04-17  319  	mmio_pgoff = PAGE_ALIGN((start & ~PAGE_MASK) + len) >> PAGE_SHIFT;
47f698a9f2fc49 drivers/video/controlfb.c Tomi Valkeinen         2013-04-17  320  	if (vma->vm_pgoff >= mmio_pgoff) {
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  321  		if (info->var.accel_flags)
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  322  			return -EINVAL;
47f698a9f2fc49 drivers/video/controlfb.c Tomi Valkeinen         2013-04-17  323  		vma->vm_pgoff -= mmio_pgoff;
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  324  		start = info->fix.mmio_start;
47f698a9f2fc49 drivers/video/controlfb.c Tomi Valkeinen         2013-04-17  325  		len = info->fix.mmio_len;
64b3d0e8122b42 drivers/video/controlfb.c Benjamin Herrenschmidt 2008-12-18 @326  		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  327  	} else {
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  328  		/* framebuffer */
64b3d0e8122b42 drivers/video/controlfb.c Benjamin Herrenschmidt 2008-12-18  329  		vma->vm_page_prot = pgprot_cached_wthru(vma->vm_page_prot);
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  330  	}
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  331  
47f698a9f2fc49 drivers/video/controlfb.c Tomi Valkeinen         2013-04-17  332  	return vm_iomap_memory(vma, start, len);
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  333  }
^1da177e4c3f41 drivers/video/controlfb.c Linus Torvalds         2005-04-16  334  

:::::: The code at line 326 was first introduced by commit
:::::: 64b3d0e8122b422e879b23d42f9e0e8efbbf9744 powerpc/mm: Rework usage of _PAGE_COHERENT/NO_CACHE/GUARDED

:::::: TO: Benjamin Herrenschmidt <benh@kernel.crashing.org>
:::::: CC: Paul Mackerras <paulus@samba.org>

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