tree:   https://github.com/tobetter/linux odroid-5.15.y
head:   bcf324ec70af843cc1e6a88e67a8b7f44c4739bb
commit: 6b8539046586e0d420e7f310df2da69b4a13d19f [46/74] ODROID-COMMON: pwm: gpio: Add a generic gpio based PWM driver
config: csky-randconfig-r034-20211103 (attached as .config)
compiler: csky-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://github.com/tobetter/linux/commit/6b8539046586e0d420e7f310df2da69b4a13d19f
        git remote add tobetter https://github.com/tobetter/linux
        git fetch --no-tags tobetter odroid-5.15.y
        git checkout 6b8539046586e0d420e7f310df2da69b4a13d19f
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=csky 

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/pwm/pwm-gpio.c:60:22: warning: no previous prototype for 'gpio_pwm_timer' [-Wmissing-prototypes]
      60 | enum hrtimer_restart gpio_pwm_timer(struct hrtimer *timer)
         |                      ^~~~~~~~~~~~~~


vim +/gpio_pwm_timer +60 drivers/pwm/pwm-gpio.c

    59	
  > 60	enum hrtimer_restart gpio_pwm_timer(struct hrtimer *timer)
    61	{
    62		struct gpio_pwm_data *gpio_data = container_of(timer,
    63							      struct gpio_pwm_data,
    64							      timer);
    65		if (!gpio_data->run) {
    66			gpio_pwm_off(gpio_data);
    67			gpio_data->pin_on = false;
    68			return HRTIMER_NORESTART;
    69		}
    70	
    71		if (!gpio_data->pin_on) {
    72			hrtimer_forward_now(&gpio_data->timer,
    73					    ns_to_ktime(gpio_data->on_time));
    74			gpio_pwm_on(gpio_data);
    75			gpio_data->pin_on = true;
    76		} else {
    77			hrtimer_forward_now(&gpio_data->timer,
    78					    ns_to_ktime(gpio_data->off_time));
    79			gpio_pwm_off(gpio_data);
    80			gpio_data->pin_on = false;
    81		}
    82	
    83		return HRTIMER_RESTART;
    84	}
    85	

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