Hi Andrzej,

I love your patch! Perhaps something to improve:

[auto build test WARNING on 48778464bb7d346b47157d21ffde2af6b2d39110]

url:    https://github.com/0day-ci/linux/commits/Andrzej-Pietrasiewicz/Stop-monitoring-disabled-devices/20200627-013944
base:    48778464bb7d346b47157d21ffde2af6b2d39110
config: arm-imx_v6_v7_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
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
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 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/thermal/thermal_core.c:462:5: warning: no previous prototype for 'thermal_zone_device_set_mode' [-Wmissing-prototypes]
     462 | int thermal_zone_device_set_mode(struct thermal_zone_device *tz,
         |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +/thermal_zone_device_set_mode +462 drivers/thermal/thermal_core.c

   461	
 > 462	int thermal_zone_device_set_mode(struct thermal_zone_device *tz,
   463					 enum thermal_device_mode mode)
   464	{
   465		int ret = 0;
   466	
   467		mutex_lock(&tz->lock);
   468	
   469		/* do nothing if mode isn't changing */
   470		if (mode == tz->mode) {
   471			mutex_unlock(&tz->lock);
   472	
   473			return ret;
   474		}
   475	
   476		if (tz->ops->set_mode)
   477			ret = tz->ops->set_mode(tz, mode);
   478	
   479		if (!ret)
   480			tz->mode = mode;
   481	
   482		mutex_unlock(&tz->lock);
   483	
   484		thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED);
   485	
   486		return ret;
   487	}
   488	

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