Re: [PATCH v5 2/2] iio: temperature: add support for MCP998X

[kernel test robot <lkp@intel.com>]

Hi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 671b9b6d7f4fe17a174c410397e72253877ca64e]

url:    https://github.com/intel-lab-lkp/linux/commits/victor-duicu-microchip-com/dt-bindings-iio-temperature-add-support-for-MCP998X/20250918-192457
base:   671b9b6d7f4fe17a174c410397e72253877ca64e
patch link:    https://lore.kernel.org/r/20250918111937.5150-3-victor.duicu%40microchip.com
patch subject: [PATCH v5 2/2] iio: temperature: add support for MCP998X
config: loongarch-allyesconfig (https://download.01.org/0day-ci/archive/20250919/202509191411.ej3JBK3f-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 7c861bcedf61607b6c087380ac711eb7ff918ca6)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250919/202509191411.ej3JBK3f-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202509191411.ej3JBK3f-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from <built-in>:3:
   In file included from include/linux/compiler_types.h:171:
   include/linux/compiler-clang.h:28:9: warning: '__SANITIZE_ADDRESS__' macro redefined [-Wmacro-redefined]
      28 | #define __SANITIZE_ADDRESS__
         |         ^
   <built-in>:371:9: note: previous definition is here
     371 | #define __SANITIZE_ADDRESS__ 1
         |         ^
>> drivers/iio/temperature/mcp9982.c:470:3: warning: label followed by a declaration is a C23 extension [-Wc23-extensions]
     470 |                 u8 bulk_read[3];
         |                 ^
   drivers/iio/temperature/mcp9982.c:488:3: warning: label followed by a declaration is a C23 extension [-Wc23-extensions]
     488 |                 unsigned long *src;
         |                 ^
>> drivers/iio/temperature/mcp9982.c:493:4: warning: variable 'src' is uninitialized when used here [-Wuninitialized]
     493 |                 *src = tmp_reg;
         |                  ^~~
   drivers/iio/temperature/mcp9982.c:488:21: note: initialize the variable 'src' to silence this warning
     488 |                 unsigned long *src;
         |                                   ^
         |                                    = NULL
   drivers/iio/temperature/mcp9982.c:741:2: warning: variable 'iio_idx' is uninitialized when used here [-Wuninitialized]
     741 |         iio_idx++;
         |         ^~~~~~~
   drivers/iio/temperature/mcp9982.c:720:30: note: initialize the variable 'iio_idx' to silence this warning
     720 |         unsigned int reg_nr, iio_idx;
         |                                     ^
         |                                      = 0
   5 warnings generated.


vim +470 drivers/iio/temperature/mcp9982.c

   426	
   427	static int mcp9982_read_raw(struct iio_dev *indio_dev,
   428				    struct iio_chan_spec const *chan, int *val,
   429				    int *val2, long mask)
   430	{
   431		unsigned int tmp_reg, reg_status;
   432		struct mcp9982_priv *priv = iio_priv(indio_dev);
   433		int ret;
   434	
   435		if (test_bit(RUN_STATE, &priv->bit_flags)) {
   436			/*
   437			 * When working in Run mode, after modifying a parameter (like sampling
   438			 * frequency) we have to wait a delay before reading the new values.
   439			 * We can't determine when the conversion is done based on the BUSY bit.
   440			 */
   441			if (test_bit(WAIT_BEFORE_READ, &priv->bit_flags)) {
   442				if (!time_after(jiffies, priv->time_limit))
   443					mdelay(jiffies_to_msecs(priv->time_limit - jiffies));
   444				clear_bit(WAIT_BEFORE_READ, &priv->bit_flags);
   445			}
   446		} else {
   447			ret = regmap_write(priv->regmap, MCP9982_ONE_SHOT_ADDR, 1);
   448			if (ret)
   449				return ret;
   450			/*
   451			 * In Standby state after writing in OneShot register wait for
   452			 * the start of conversion and then poll the BUSY bit.
   453			 */
   454			mdelay(125);
   455			ret = regmap_read_poll_timeout(priv->regmap, MCP9982_STATUS_ADDR,
   456						       reg_status, !(reg_status & MCP9982_STATUS_BUSY),
   457						       mcp9982_delay_ms[priv->sampl_idx] * USEC_PER_MSEC,
   458						       0);
   459			if (ret)
   460				return ret;
   461		}
   462		guard(mutex)(&priv->lock);
   463	
   464		switch (mask) {
   465		case IIO_CHAN_INFO_RAW:
   466			/*
   467			 * The Block Read Protocol first returns the number of user readable
   468			 * bytes, held in bulk_read[0], followed by the data.
   469			 */
 > 470			u8 bulk_read[3];
   471	
   472			ret = regmap_bulk_read(priv->regmap, MCP9982_TEMP_MEM_BLOCK_ADDR(chan->channel),
   473					       &bulk_read, sizeof(bulk_read));
   474			if (ret)
   475				return ret;
   476	
   477			*val = (bulk_read[1] << 8) + (bulk_read[2]);
   478			return IIO_VAL_INT;
   479		case IIO_CHAN_INFO_SCALE:
   480			*val = 0;
   481			*val2 = MCP9982_SCALE;
   482			return IIO_VAL_INT_PLUS_NANO;
   483		case IIO_CHAN_INFO_SAMP_FREQ:
   484			*val = mcp9982_conv_rate[priv->sampl_idx][0];
   485			*val2 = mcp9982_conv_rate[priv->sampl_idx][1];
   486			return IIO_VAL_INT_PLUS_MICRO;
   487		case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
   488			unsigned long *src;
   489	
   490			ret = regmap_read(priv->regmap, MCP9982_RUNNING_AVG_ADDR, &tmp_reg);
   491			if (ret)
   492				return ret;
 > 493			*src = tmp_reg;
   494			*val = mcp9982_3db_values_map_tbl[priv->sampl_idx][bitmap_weight(src, 2)][0];
   495			*val2 = mcp9982_3db_values_map_tbl[priv->sampl_idx][bitmap_weight(src, 2)][1];
   496			return IIO_VAL_INT_PLUS_MICRO;
   497		case IIO_CHAN_INFO_OFFSET:
   498			*val = MCP9982_OFFSET;
   499			return IIO_VAL_INT;
   500		default:
   501			return -EINVAL;
   502		}
   503	}
   504	

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