[intel-linux-intel-lts:5.4/yocto 1/10] drivers/ptp/ptp-intel-tgpio.c:215:6: warning: variable 'isgn' is used uninitialized whenever 'if' condition is false

[intel-linux-intel-lts:5.4/yocto 1/10] drivers/ptp/ptp-intel-tgpio.c:215:6: 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: 7bd792a514cfed284104c5606fedabd00e187814 [1/10] drivers/ptp: Add PSE Time-Aware GPIO Driver
config: x86_64-randconfig-r022-20210906 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 6fe2beba7d2a41964af658c8c59dd172683ef739)
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/intel/linux-intel-lts/commit/7bd792a514cfed284104c5606fedabd00e187814
        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 7bd792a514cfed284104c5606fedabd00e187814
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross 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.c:215:6: warning: variable 'isgn' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           if (scaled_ppm < 0) {
               ^~~~~~~~~~~~~~
   drivers/ptp/ptp-intel-tgpio.c:228:9: note: uninitialized use occurs here
           reg |= isgn << 31;
                  ^~~~
   drivers/ptp/ptp-intel-tgpio.c:215:2: note: remove the 'if' if its condition is always true
           if (scaled_ppm < 0) {
           ^~~~~~~~~~~~~~~~~~~~
   drivers/ptp/ptp-intel-tgpio.c:212:13: note: initialize the variable 'isgn' to silence this warning
           bool                    isgn;
                                       ^
                                        = 0
   1 warning generated.


vim +215 drivers/ptp/ptp-intel-tgpio.c

   206	
   207	static int intel_tgpio_adjfine(struct ptp_clock_info *info, long scaled_ppm)
   208	{
   209		struct intel_tgpio	*tgpio = to_intel_tgpio(info);
   210		unsigned long		flags;
   211		u32			reg;
   212		bool			isgn;
   213	
   214		spin_lock_irqsave(&tgpio->lock, flags);
 > 215		if (scaled_ppm < 0) {
   216			isgn = true;
   217			scaled_ppm = -scaled_ppm;
   218		}
   219	
   220		/*
   221		 * HW uses a 200MHz clock, meaning it has a 5ns period. Just
   222		 * multiply scaled_ppm by 5 to get our increment.
   223		 */
   224		reg = 5 * scaled_ppm;
   225	
   226		/* bit 31 is sign bit */
   227		reg &= ~BIT(31);
   228		reg |= isgn << 31;
   229	
   230		intel_tgpio_writel(tgpio->base, TIMINCA_GLOBAL, reg);
   231		spin_unlock_irqrestore(&tgpio->lock, flags);
   232	
   233		return 0;
   234	}
   235	

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

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