Re: [PATCH 1/2] tty: serial: imx: Only configure the wake register when device is set as wakeup source

[kernel test robot <lkp@intel.com>]

Hi Sherry,

kernel test robot noticed the following build warnings:

[auto build test WARNING on shawnguo/for-next]
[also build test WARNING on tty/tty-testing tty/tty-next tty/tty-linus usb/usb-testing usb/usb-next usb/usb-linus linus/master v6.17-rc7 next-20250922]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sherry-Sun/tty-serial-imx-Only-configure-the-wake-register-when-device-is-set-as-wakeup-source/20250923-111951
base:   https://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux.git for-next
patch link:    https://lore.kernel.org/r/20250923031613.2448073-2-sherry.sun%40nxp.com
patch subject: [PATCH 1/2] tty: serial: imx: Only configure the wake register when device is set as wakeup source
config: arm-randconfig-004-20250923 (https://download.01.org/0day-ci/archive/20250924/202509240009.Q4htWwxE-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project cafc064fc7a96b3979a023ddae1da2b499d6c954)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250924/202509240009.Q4htWwxE-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202509240009.Q4htWwxE-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/tty/serial/imx.c:2707:6: warning: variable 'may_wake' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
    2707 |         if (tty) {
         |             ^~~
   drivers/tty/serial/imx.c:2714:7: note: uninitialized use occurs here
    2714 |         if (!may_wake)
         |              ^~~~~~~~
   drivers/tty/serial/imx.c:2707:2: note: remove the 'if' if its condition is always true
    2707 |         if (tty) {
         |         ^~~~~~~~
   drivers/tty/serial/imx.c:2704:15: note: initialize the variable 'may_wake' to silence this warning
    2704 |         bool may_wake;
         |                      ^
         |                       = 0
   1 warning generated.


vim +2707 drivers/tty/serial/imx.c

  2696	
  2697	/* called with irq off */
  2698	static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)
  2699	{
  2700		struct tty_port *port = &sport->port.state->port;
  2701		struct tty_struct *tty;
  2702		struct device *tty_dev;
  2703		u32 ucr3;
  2704		bool may_wake;
  2705	
  2706		tty = tty_port_tty_get(port);
> 2707		if (tty) {
  2708			tty_dev = tty->dev;
  2709			may_wake = tty_dev && device_may_wakeup(tty_dev);
  2710			tty_kref_put(tty);
  2711		}
  2712	
  2713		/* only configure the wake register when device set as wakeup source */
  2714		if (!may_wake)
  2715			return;
  2716	
  2717		uart_port_lock_irq(&sport->port);
  2718	
  2719		ucr3 = imx_uart_readl(sport, UCR3);
  2720		if (on) {
  2721			imx_uart_writel(sport, USR1_AWAKE, USR1);
  2722			ucr3 |= UCR3_AWAKEN;
  2723		} else {
  2724			ucr3 &= ~UCR3_AWAKEN;
  2725		}
  2726		imx_uart_writel(sport, ucr3, UCR3);
  2727	
  2728		if (sport->have_rtscts) {
  2729			u32 ucr1 = imx_uart_readl(sport, UCR1);
  2730			if (on) {
  2731				imx_uart_writel(sport, USR1_RTSD, USR1);
  2732				ucr1 |= UCR1_RTSDEN;
  2733			} else {
  2734				ucr1 &= ~UCR1_RTSDEN;
  2735			}
  2736			imx_uart_writel(sport, ucr1, UCR1);
  2737		}
  2738	
  2739		uart_port_unlock_irq(&sport->port);
  2740	}
  2741	

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