[intel-linux-intel-lts:5.4/yocto 5/10] drivers/ptp/ptp-intel-tgpio-plat.c:234:6: warning: variable 'isgn' is used uninitialized whenever 'if' condition is false

[intel-linux-intel-lts:5.4/yocto 5/10] drivers/ptp/ptp-intel-tgpio-plat.c:234:6: warning: variable 'isgn' is used uninitialized whenever 'if' condition is false

[kernel test robot]

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tree:   https://github.com/intel/linux-intel-lts.git 5.4/yocto
head:   5342fd3d769c58688aad5088b77b3c9f44438ef7
commit: e3b73159b8cfd2c940dd6e55702754c16f1f3923 [5/10] mfd: intel-ehl-gpio: Introduce MFD framework to PSE GPIO/TGPIO
config: x86_64-randconfig-r026-20210514 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 425781bce01f2f1d5f553d3b2bf9ebbd6e15068c)
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 x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/intel/linux-intel-lts/commit/e3b73159b8cfd2c940dd6e55702754c16f1f3923
        git remote add intel-linux-intel-lts https://github.com/intel/linux-intel-lts.git
        git fetch --no-tags intel-linux-intel-lts 5.4/yocto
        git checkout e3b73159b8cfd2c940dd6e55702754c16f1f3923
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=x86_64 

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/ptp/ptp-intel-tgpio-plat.c:234:6: warning: variable 'isgn' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           if (scaled_ppm < 0) {
               ^~~~~~~~~~~~~~
   drivers/ptp/ptp-intel-tgpio-plat.c:247:9: note: uninitialized use occurs here
           reg |= isgn << 31;
                  ^~~~
   drivers/ptp/ptp-intel-tgpio-plat.c:234:2: note: remove the 'if' if its condition is always true
           if (scaled_ppm < 0) {
           ^~~~~~~~~~~~~~~~~~~~
   drivers/ptp/ptp-intel-tgpio-plat.c:229:13: note: initialize the variable 'isgn' to silence this warning
           bool                    isgn;
                                       ^
                                        = 0
   1 warning generated.


vim +234 drivers/ptp/ptp-intel-tgpio-plat.c

   223	
   224	static int intel_tgpio_adjfine(struct ptp_clock_info *info, long scaled_ppm)
   225	{
   226		struct intel_tgpio	*tgpio = to_intel_tgpio(info);
   227		unsigned long		flags;
   228		u32			reg;
   229		bool			isgn;
   230	
   231		pm_runtime_get_sync(tgpio->dev->parent);
   232	
   233		spin_lock_irqsave(&tgpio->lock, flags);
 > 234		if (scaled_ppm < 0) {
   235			isgn = true;
   236			scaled_ppm = -scaled_ppm;
   237		}
   238	
   239		/*
   240		 * HW uses a 200MHz clock, meaning it has a 5ns period. Just
   241		 * multiply scaled_ppm by 5 to get our increment.
   242		 */
   243		reg = 5 * scaled_ppm;
   244	
   245		/* bit 31 is sign bit */
   246		reg &= ~BIT(31);
   247		reg |= isgn << 31;
   248	
   249		intel_tgpio_writel(tgpio->base, TIMINCA_GLOBAL, reg);
   250		spin_unlock_irqrestore(&tgpio->lock, flags);
   251	
   252		pm_runtime_put(tgpio->dev->parent);
   253	
   254		return 0;
   255	}
   256	

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

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