Hi "Uwe,

I love your patch! Perhaps something to improve:

[auto build test WARNING on tty/tty-testing]
[also build test WARNING on pavel-linux-leds/for-next linus/master j.anaszewski-leds/for-next v5.9 next-20201012]
[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/Uwe-Kleine-K-nig/leds-trigger-implement-a-tty-trigger/20201012-203510
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
config: ia64-allmodconfig (attached as .config)
compiler: ia64-linux-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
        # https://github.com/0day-ci/linux/commit/4185c273a8de0340cee6655a363f98c3737665d0
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Uwe-Kleine-K-nig/leds-trigger-implement-a-tty-trigger/20201012-203510
        git checkout 4185c273a8de0340cee6655a363f98c3737665d0
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=ia64 

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/leds/trigger/ledtrig-tty.c: In function 'ledtrig_tty_work':
>> drivers/leds/trigger/ledtrig-tty.c:92:7: warning: variable 'firstrun' set but not used [-Wunused-but-set-variable]
      92 |  bool firstrun = false;
         |       ^~~~~~~~

vim +/firstrun +92 drivers/leds/trigger/ledtrig-tty.c

    85	
    86	static void ledtrig_tty_work(struct work_struct *work)
    87	{
    88		struct ledtrig_tty_data *trigger_data =
    89			container_of(work, struct ledtrig_tty_data, dwork.work);
    90		struct serial_icounter_struct icount;
    91		int ret;
  > 92		bool firstrun = false;
    93	
    94		mutex_lock(&trigger_data->mutex);
    95	
    96		BUG_ON(!trigger_data->ttyname);
    97	
    98		/* try to get the tty corresponding to $ttyname */
    99		if (!trigger_data->tty) {
   100			dev_t devno;
   101			struct tty_struct *tty;
   102			int ret;
   103	
   104			firstrun = true;
   105	
   106			ret = tty_dev_name_to_number(trigger_data->ttyname, &devno);
   107			if (ret < 0)
   108				/*
   109				 * A device with this name might appear later, so keep
   110				 * retrying.
   111				 */
   112				goto out;
   113	
   114			tty = tty_kopen_shared(devno);
   115			if (IS_ERR(tty) || !tty)
   116				/* What to do? retry or abort */
   117				goto out;
   118	
   119			trigger_data->tty = tty;
   120		}
   121	
   122		ret = tty_get_icount(trigger_data->tty, &icount);
   123		if (ret) {
   124			mutex_unlock(&trigger_data->mutex);
   125			dev_info(trigger_data->tty->dev, "Failed to get icount, stopped polling\n");
   126			mutex_unlock(&trigger_data->mutex);
   127			return;
   128		}
   129	
   130		if (icount.rx != trigger_data->rx ||
   131		    icount.tx != trigger_data->tx) {
   132			led_set_brightness(trigger_data->led_cdev, LED_ON);
   133	
   134			trigger_data->rx = icount.rx;
   135			trigger_data->tx = icount.tx;
   136		} else {
   137			led_set_brightness(trigger_data->led_cdev, LED_OFF);
   138		}
   139	
   140	out:
   141		mutex_unlock(&trigger_data->mutex);
   142		schedule_delayed_work(&trigger_data->dwork, msecs_to_jiffies(100));
   143	}
   144	

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