Hi Mikko,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on usb/usb-testing]
[also build test WARNING on tegra/for-next linux/master linus/master v5.11-rc7 next-20210212]
[cannot apply to tty/tty-testing]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Mikko-Perttunen/tty-serial-Add-earlycon-driver-for-Tegra-Combined-UART/20210213-200425
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
config: arm-randconfig-r016-20210213 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c9439ca36342fb6013187d0a69aef92736951476)
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://github.com/0day-ci/linux/commit/889104c3001a64bab09c4ac82aed58f1d98ec77a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Mikko-Perttunen/tty-serial-Add-earlycon-driver-for-Tegra-Combined-UART/20210213-200425
        git checkout 889104c3001a64bab09c4ac82aed58f1d98ec77a
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/tty/serial/tegra-tcu-earlycon.c:62:12: warning: no previous prototype for function 'early_tegra_combined_uart_setup' [-Wmissing-prototypes]
   int __init early_tegra_combined_uart_setup(struct earlycon_device *device, const char *options)
              ^
   drivers/tty/serial/tegra-tcu-earlycon.c:62:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int __init early_tegra_combined_uart_setup(struct earlycon_device *device, const char *options)
   ^
   static 
   1 warning generated.

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for ARM_CPU_SUSPEND
   Depends on ARCH_SUSPEND_POSSIBLE
   Selected by
   - ARM_QCOM_SPM_CPUIDLE && CPU_IDLE && (ARM || ARM64) && (ARCH_QCOM || COMPILE_TEST && !ARM64


vim +/early_tegra_combined_uart_setup +62 drivers/tty/serial/tegra-tcu-earlycon.c

    61	
  > 62	int __init early_tegra_combined_uart_setup(struct earlycon_device *device, const char *options)
    63	{
    64		if (!(device->port.membase))
    65			return -ENODEV;
    66	
    67		device->con->write = early_tcu_write;
    68	
    69		return 0;
    70	}
    71	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org