Hi Tomasz,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on iio/togreg]
[also build test WARNING on v4.20-rc4 next-20181123]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Tomasz-Duszynski/add-support-for-Sensirion-SPS30-PM-sensor/20181125-172634
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
config: x86_64-allmodconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

>> drivers/iio/chemical/sps30.c:69:26: warning: Variable length array is used.
   drivers/iio/chemical/sps30.c: In function 'sps30_read_raw':
   drivers/iio/chemical/sps30.c:237:7: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
       if (ret)
          ^

vim +69 drivers/iio/chemical/sps30.c

0e4f3167f Tomasz Duszynski 2018-11-24   64  
0e4f3167f Tomasz Duszynski 2018-11-24   65  static int sps30_write_then_read(struct sps30_state *state, u8 *buf,
0e4f3167f Tomasz Duszynski 2018-11-24   66  				 int buf_size, u8 *data, int data_size)
0e4f3167f Tomasz Duszynski 2018-11-24   67  {
0e4f3167f Tomasz Duszynski 2018-11-24   68  	/* every two received data bytes are checksummed */
0e4f3167f Tomasz Duszynski 2018-11-24  @69  	u8 tmp[data_size + data_size / 2];
0e4f3167f Tomasz Duszynski 2018-11-24   70  	int ret, i;
0e4f3167f Tomasz Duszynski 2018-11-24   71  
0e4f3167f Tomasz Duszynski 2018-11-24   72  	/*
0e4f3167f Tomasz Duszynski 2018-11-24   73  	 * Sensor does not support repeated start so instead of
0e4f3167f Tomasz Duszynski 2018-11-24   74  	 * sending two i2c messages in a row we just send one by one.
0e4f3167f Tomasz Duszynski 2018-11-24   75  	 */
0e4f3167f Tomasz Duszynski 2018-11-24   76  	ret = i2c_master_send(state->client, buf, buf_size);
0e4f3167f Tomasz Duszynski 2018-11-24   77  	if (ret != buf_size)
0e4f3167f Tomasz Duszynski 2018-11-24   78  		return ret < 0 ? ret : -EIO;
0e4f3167f Tomasz Duszynski 2018-11-24   79  
0e4f3167f Tomasz Duszynski 2018-11-24   80  	if (!data)
0e4f3167f Tomasz Duszynski 2018-11-24   81  		return 0;
0e4f3167f Tomasz Duszynski 2018-11-24   82  
0e4f3167f Tomasz Duszynski 2018-11-24   83  	ret = i2c_master_recv(state->client, tmp, sizeof(tmp));
0e4f3167f Tomasz Duszynski 2018-11-24   84  	if (ret != sizeof(tmp))
0e4f3167f Tomasz Duszynski 2018-11-24   85  		return ret < 0 ? ret : -EIO;
0e4f3167f Tomasz Duszynski 2018-11-24   86  
0e4f3167f Tomasz Duszynski 2018-11-24   87  	for (i = 0; i < sizeof(tmp); i += 3) {
0e4f3167f Tomasz Duszynski 2018-11-24   88  		u8 crc = crc8(sps30_crc8_table, &tmp[i], 2, CRC8_INIT_VALUE);
0e4f3167f Tomasz Duszynski 2018-11-24   89  
0e4f3167f Tomasz Duszynski 2018-11-24   90  		if (crc != tmp[i + 2]) {
0e4f3167f Tomasz Duszynski 2018-11-24   91  			dev_err(&state->client->dev,
0e4f3167f Tomasz Duszynski 2018-11-24   92  				"data integrity check failed\n");
0e4f3167f Tomasz Duszynski 2018-11-24   93  			return -EIO;
0e4f3167f Tomasz Duszynski 2018-11-24   94  		}
0e4f3167f Tomasz Duszynski 2018-11-24   95  
0e4f3167f Tomasz Duszynski 2018-11-24   96  		*data++ = tmp[i];
0e4f3167f Tomasz Duszynski 2018-11-24   97  		*data++ = tmp[i + 1];
0e4f3167f Tomasz Duszynski 2018-11-24   98  	}
0e4f3167f Tomasz Duszynski 2018-11-24   99  
0e4f3167f Tomasz Duszynski 2018-11-24  100  	return 0;
0e4f3167f Tomasz Duszynski 2018-11-24  101  }
0e4f3167f Tomasz Duszynski 2018-11-24  102  

:::::: The code at line 69 was first introduced by commit
:::::: 0e4f3167f739fa067d7e1ba672f0b46569d04d84 iio: chemical: add support for Sensirion SPS30 sensor

:::::: TO: Tomasz Duszynski <tduszyns@gmail.com>
:::::: CC: 0day robot <lkp@intel.com>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation