Hi Arnd, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 01f856ae6d0ca5ad0505b79bf2d22d7ca439b2a1 commit: d7445676e86900f8dc363825033ff62416c216e0 ARM: versatile: move integrator/realview/vexpress to versatile date: 8 months ago config: arm-versatile_defconfig compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 6e4cea55f0d1104408b26ac574566a0e4de48036) 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 arm cross compiling tool for clang build # apt-get install binutils-arm-linux-gnueabi # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d7445676e86900f8dc363825033ff62416c216e0 git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout d7445676e86900f8dc363825033ff62416c216e0 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot All warnings (new ones prefixed by >>): >> arch/arm/mach-versatile/versatile.c:56:14: warning: no previous prototype for function 'mmc_status' [-Wmissing-prototypes] unsigned int mmc_status(struct device *dev) ^ arch/arm/mach-versatile/versatile.c:56:1: note: declare 'static' if the function is not intended to be used outside of this translation unit unsigned int mmc_status(struct device *dev) ^ static 1 warning generated. vim +/mmc_status +56 arch/arm/mach-versatile/versatile.c a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 55 a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 @56 unsigned int mmc_status(struct device *dev) a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 57 { a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 58 struct amba_device *adev = container_of(dev, struct amba_device, dev); a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 59 u32 mask; a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 60 a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 61 if (adev->res.start == VERSATILE_MMCI0_BASE) a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 62 mask = 1; a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 63 else a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 64 mask = 2; a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 65 a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 66 return readl(versatile_sys_base + VERSATILE_SYS_MCI_OFFSET) & mask; a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 67 } a7096789211193 arch/arm/mach-versatile/versatile_dt.c Rob Herring 2015-12-08 68 :::::: The code at line 56 was first introduced by commit :::::: a70967892111934e292485ce84f1bab38cc55380 ARM: versatile: merge mach code into a single file :::::: TO: Rob Herring :::::: CC: Arnd Bergmann -- 0-DAY CI Kernel Test Service https://01.org/lkp