linux-kernel - drivers/input/touchscreen/ads7846.c:705:24: warning: taking address of packed member 'data' of class or structure 'ads7846_buf' may result in an unaligned pointer value

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Date:   Fri, 2 Jul 2021 03:21:43 +0800
From:   kernel test robot <lkp@...el.com>
To:     Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     clang-built-linux@...glegroups.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: drivers/input/touchscreen/ads7846.c:705:24: warning: taking address
 of packed member 'data' of class or structure 'ads7846_buf' may result in an
 unaligned pointer value

Hi Oleksij,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   dbe69e43372212527abf48609aba7fc39a6daa27
commit: 6965eece2a89c3f1d00881c6052ee1e987870c08 Input: ads7846 - convert to one message
date:   5 months ago
config: mips-buildonly-randconfig-r005-20210630 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 8d21d5472501460933e78aead04cf59579025ba4)
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 mips cross compiling tool for clang build
        # apt-get install binutils-mips-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6965eece2a89c3f1d00881c6052ee1e987870c08
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 6965eece2a89c3f1d00881c6052ee1e987870c08
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips 

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/input/touchscreen/ads7846.c:705:24: warning: taking address of packed member 'data' of class or structure 'ads7846_buf' may result in an unaligned pointer value [-Waddress-of-packed-member]
           value = be16_to_cpup(&buf->data);
                                 ^~~~~~~~~
   1 warning generated.


vim +705 drivers/input/touchscreen/ads7846.c

   700	
   701	static int ads7846_get_value(struct ads7846_buf *buf)
   702	{
   703		int value;
   704	
 > 705		value = be16_to_cpup(&buf->data);
   706	
   707		/* enforce ADC output is 12 bits width */
   708		return (value >> 3) & 0xfff;
   709	}
   710	

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

Download attachment ".config.gz" of type "application/gzip" (44261 bytes)