tree:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git debugfs_cleanup
head:   2af10af50dae1d4154ed0053ac8bd15d773b86e4
commit: 2f52245a70e7911407dfbea078f1a012764f8a42 [3/13] drm: make .debugfs_init and drm_debugfs_create_files() return void
config: nds32-allmodconfig (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
        git checkout 2f52245a70e7911407dfbea078f1a012764f8a42
        # 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 errors (new ones prefixed by >>):

>> drivers/gpu/drm/tiny/hx8357d.c:200:19: error: initialization of 'void (*)(struct drm_minor *)' from incompatible pointer type 'int (*)(struct drm_minor *)' [-Werror=incompatible-pointer-types]
     .debugfs_init  = mipi_dbi_debugfs_init,
                      ^~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/tiny/hx8357d.c:200:19: note: (near initialization for 'hx8357d_driver.debugfs_init')
   cc1: some warnings being treated as errors
--
>> drivers/gpu/drm/tiny/ili9341.c:156:19: error: initialization of 'void (*)(struct drm_minor *)' from incompatible pointer type 'int (*)(struct drm_minor *)' [-Werror=incompatible-pointer-types]
     .debugfs_init  = mipi_dbi_debugfs_init,
                      ^~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/tiny/ili9341.c:156:19: note: (near initialization for 'ili9341_driver.debugfs_init')
   cc1: some warnings being treated as errors
--
>> drivers/gpu/drm/tiny/mi0283qt.c:160:19: error: initialization of 'void (*)(struct drm_minor *)' from incompatible pointer type 'int (*)(struct drm_minor *)' [-Werror=incompatible-pointer-types]
     .debugfs_init  = mipi_dbi_debugfs_init,
                      ^~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/tiny/mi0283qt.c:160:19: note: (near initialization for 'mi0283qt_driver.debugfs_init')
   cc1: some warnings being treated as errors
--
>> drivers/gpu/drm/tiny/st7586.c:298:19: error: initialization of 'void (*)(struct drm_minor *)' from incompatible pointer type 'int (*)(struct drm_minor *)' [-Werror=incompatible-pointer-types]
     .debugfs_init  = mipi_dbi_debugfs_init,
                      ^~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/tiny/st7586.c:298:19: note: (near initialization for 'st7586_driver.debugfs_init')
   cc1: some warnings being treated as errors
--
>> drivers/gpu/drm/tiny/st7735r.c:130:19: error: initialization of 'void (*)(struct drm_minor *)' from incompatible pointer type 'int (*)(struct drm_minor *)' [-Werror=incompatible-pointer-types]
     .debugfs_init  = mipi_dbi_debugfs_init,
                      ^~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/tiny/st7735r.c:130:19: note: (near initialization for 'st7735r_driver.debugfs_init')
   cc1: some warnings being treated as errors

vim +200 drivers/gpu/drm/tiny/hx8357d.c

f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  194  
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  195  static struct drm_driver hx8357d_driver = {
0424fdaf883a68 drivers/gpu/drm/tinydrm/hx8357d.c Daniel Vetter  2019-06-17  196  	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  197  	.fops			= &hx8357d_fops,
3eba3922819fe2 drivers/gpu/drm/tinydrm/hx8357d.c Noralf Trønnes 2019-02-25  198  	.release		= mipi_dbi_release,
3db8d37dd84e93 drivers/gpu/drm/tinydrm/hx8357d.c Noralf Trønnes 2018-11-10  199  	DRM_GEM_CMA_VMAP_DRIVER_OPS,
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24 @200  	.debugfs_init		= mipi_dbi_debugfs_init,
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  201  	.name			= "hx8357d",
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  202  	.desc			= "HX8357D",
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  203  	.date			= "20181023",
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  204  	.major			= 1,
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  205  	.minor			= 0,
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  206  };
f300c86e33a686 drivers/gpu/drm/tinydrm/hx8357d.c Eric Anholt    2018-10-24  207  

:::::: The code at line 200 was first introduced by commit
:::::: f300c86e33a686c7abcf0c37deee04ef666ed78b drm: Add an hx8367d tinydrm driver.

:::::: TO: Eric Anholt <eric@anholt.net>
:::::: CC: Eric Anholt <eric@anholt.net>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation