tree: https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git gpiochip-no-driver-h head: 3357a6b5d4c178fcbe95eb72c4e653b3a5b41569 commit: 3357a6b5d4c178fcbe95eb72c4e653b3a5b41569 [2/2] See what explodes if we apply this patch config: mips-capcella_defconfig (attached as .config) compiler: mipsel-linux-gcc (GCC) 11.2.0 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 # https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git/com... git remote add gpio https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git git fetch --no-tags gpio gpiochip-no-driver-h git checkout 3357a6b5d4c178fcbe95eb72c4e653b3a5b41569 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from include/linux/gpio.h:62, from drivers/gpio/gpiolib.c:14: include/asm-generic/gpio.h: In function 'gpio_to_chip': include/asm-generic/gpio.h:58:16: error: implicit declaration of function 'gpiod_to_chip'; did you mean 'gpio_to_chip'? [-Werror=implicit-function-declaration] 58 | return gpiod_to_chip(gpio_to_desc(gpio)); | ^~~~~~~~~~~~~ | gpio_to_chip include/asm-generic/gpio.h:58:16: warning: returning 'int' from a function with return type 'struct gpio_chip *' makes pointer from integer without a cast [-Wint-conversion] 58 | return gpiod_to_chip(gpio_to_desc(gpio)); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from drivers/gpio/gpiolib.c:18: include/linux/gpio/driver.h: At top level: 704 | struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc); | ^~~~~~~~~~~~~ In file included from include/linux/gpio.h:62, from drivers/gpio/gpiolib.c:14: include/asm-generic/gpio.h:58:16: note: previous implicit declaration of 'gpiod_to_chip' with type 'int()' 58 | return gpiod_to_chip(gpio_to_desc(gpio)); | ^~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +704 include/linux/gpio/driver.h c7663fa2a6631e YueHaibing 2019-08-22 702 9091373ab7ea27 Masahiro Yamada 2019-07-30 703 9091373ab7ea27 Masahiro Yamada 2019-07-30 @704 struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc); 9091373ab7ea27 Masahiro Yamada 2019-07-30 705 :::::: The code at line 704 was first introduced by commit :::::: 9091373ab7ea27cad381ce71aa37de6b9e687e81 gpio: remove less important #ifdef around declarations :::::: TO: Masahiro Yamada <yamada.masahiro(a)socionext.com&gt; :::::: CC: Bartosz Golaszewski <bgolaszewski(a)baylibre.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org