linux-kernel - [iio:testing 26/30] drivers/iio/adc/at91-sama5d2_adc.c:722:11: warning: variable 'val' is used uninitialized whenever 'if' condition is false

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Date:   Tue, 31 Aug 2021 01:57:16 +0800
From:   kernel test robot <lkp@...el.com>
To:     Eugen Hristev <eugen.hristev@...rochip.com>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: [iio:testing 26/30] drivers/iio/adc/at91-sama5d2_adc.c:722:11:
 warning: variable 'val' is used uninitialized whenever 'if' condition is
 false

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git testing
head:   4fd351a1ce67ab1229d392047c3ef8e524dab3dd
commit: 29edec2b98fff8ce5145a8585dfc363564704d14 [26/30] iio: adc: at91-sama5d2_adc: convert to platform specific data structures
config: hexagon-buildonly-randconfig-r004-20210830 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 4b1fde8a2b681dad2ce0c082a5d6422caa06b0bc)
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://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/?id=29edec2b98fff8ce5145a8585dfc363564704d14
        git remote add iio https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git
        git fetch --no-tags iio testing
        git checkout 29edec2b98fff8ce5145a8585dfc363564704d14
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=hexagon 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> drivers/iio/adc/at91-sama5d2_adc.c:722:11: warning: variable 'val' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           else if (reg == st->soc_info.platform->layout->YPOSR)
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/iio/adc/at91-sama5d2_adc.c:725:7: note: uninitialized use occurs here
           if (!val)
                ^~~
   drivers/iio/adc/at91-sama5d2_adc.c:722:7: note: remove the 'if' if its condition is always true
           else if (reg == st->soc_info.platform->layout->YPOSR)
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/iio/adc/at91-sama5d2_adc.c:711:9: note: initialize the variable 'val' to silence this warning
           u32 val;
                  ^
                   = 0
   1 warning generated.


vim +722 drivers/iio/adc/at91-sama5d2_adc.c

   708	
   709	static u16 at91_adc_touch_pos(struct at91_adc_state *st, int reg)
   710	{
   711		u32 val;
   712		u32 scale, result, pos;
   713	
   714		/*
   715		 * to obtain the actual position we must divide by scale
   716		 * and multiply with max, where
   717		 * max = 2^AT91_SAMA5D2_MAX_POS_BITS - 1
   718		 */
   719		/* first half of register is the x or y, second half is the scale */
   720		if (reg == st->soc_info.platform->layout->XPOSR)
   721			val = at91_adc_readl(st, XPOSR);
 > 722		else if (reg == st->soc_info.platform->layout->YPOSR)
   723			val = at91_adc_readl(st, YPOSR);
   724	
   725		if (!val)
   726			dev_dbg(&st->indio_dev->dev, "pos is 0\n");
   727	
   728		pos = val & AT91_SAMA5D2_XYZ_MASK;
   729		result = (pos << AT91_SAMA5D2_MAX_POS_BITS) - pos;
   730		scale = (val >> 16) & AT91_SAMA5D2_XYZ_MASK;
   731		if (scale == 0) {
   732			dev_err(&st->indio_dev->dev, "scale is 0\n");
   733			return 0;
   734		}
   735		result /= scale;
   736	
   737		return result;
   738	}
   739	

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

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