tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 4333a9b0b67bb4e8bcd91bdd80da80b0ec151162 commit: 79591b7db21d255db158afaa48c557dcab631a1c spi: Add a PTP system timestamp to the transfer structure date: 9 months ago config: x86_64-randconfig-a014-20200620 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project f5bbe390d23d7da0ffb110cdb24b583c2dc87eba) 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 # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu git checkout 79591b7db21d255db158afaa48c557dcab631a1c # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): static int ld9040_prepare(struct drm_panel *panel) ^ 1 warning generated. vim +/ld9040_prepare +240 drivers/gpu/drm/panel/panel-samsung-ld9040.c ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 239 099b3e8699322e drivers/gpu/drm/panel/panel-ld9040.c Ajay Kumar 2014-07-31 @240 static int ld9040_prepare(struct drm_panel *panel) ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 241 { ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 242 struct ld9040 *ctx = panel_to_ld9040(panel); ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 243 int ret; ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 244 ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 245 ret = ld9040_power_on(ctx); ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 246 if (ret < 0) ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 247 return ret; ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 248 ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 249 ld9040_init(ctx); ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 250 ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 251 ret = ld9040_clear_error(ctx); ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 252 ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 253 if (ret < 0) 8141028278c2ea drivers/gpu/drm/panel/panel-ld9040.c Ajay Kumar 2014-07-31 254 ld9040_unprepare(panel); ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 255 ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 256 return ret; ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 257 } ff219937763253 drivers/gpu/drm/panel/panel-ld9040.c Andrzej Hajda 2014-03-26 258 :::::: The code at line 240 was first introduced by commit :::::: 099b3e8699322efb7229913d2c1651588205f182 drm/panel: ld9040: Add dummy prepare and unprepare routines :::::: TO: Ajay Kumar <ajaykumar.rs(a)samsung.com&gt; :::::: CC: Thierry Reding <treding(a)nvidia.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org