Re: [PATCH 2/3] iio: accel: kionix-kx022a: Add chip_info structure

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

Hi Mehdi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on jic23-iio/togreg]
[also build test WARNING on next-20230316]
[cannot apply to linus/master v6.3-rc2]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Mehdi-Djait/dt-bindings-iio-Add-KX132-accelerometer/20230317-075056
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
patch link:    https://lore.kernel.org/r/3ddca10a4c03c3a64afb831cc9dd1e01fe89d305.1679009443.git.mehdi.djait.k%40gmail.com
patch subject: [PATCH 2/3] iio: accel: kionix-kx022a: Add chip_info structure
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20230317/202303170813.jSOLGCL5-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 12.1.0
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-lab-lkp/linux/commit/40c75341c42d0e5bea5d73961202978a4be41cd2
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Mehdi-Djait/dt-bindings-iio-Add-KX132-accelerometer/20230317-075056
        git checkout 40c75341c42d0e5bea5d73961202978a4be41cd2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash drivers/iio/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303170813.jSOLGCL5-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/iio/accel/kionix-kx022a.c: In function '__kx022a_fifo_flush':
>> drivers/iio/accel/kionix-kx022a.c:598:9: warning: ISO C90 forbids variable length array 'buffer' [-Wvla]
     598 |         __le16 buffer[data->chip_info->fifo_length * 3];
         |         ^~~~~~
--
   drivers/iio/accel/kionix-kx022a-i2c.c: In function 'kx022a_i2c_probe':
>> drivers/iio/accel/kionix-kx022a-i2c.c:27:19: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
      27 |         chip_info = device_get_match_data(&i2c->dev);
         |                   ^
   drivers/iio/accel/kionix-kx022a-i2c.c:29:27: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
      29 |                 chip_info = (const struct kx022a_chip_info *) id->driver_data;
         |                           ^
--
   drivers/iio/accel/kionix-kx022a-spi.c: In function 'kx022a_spi_probe':
>> drivers/iio/accel/kionix-kx022a-spi.c:27:19: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
      27 |         chip_info = device_get_match_data(&spi->dev);
         |                   ^
   drivers/iio/accel/kionix-kx022a-spi.c:29:27: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
      29 |                 chip_info = (const struct kx022a_chip_info *) id->driver_data;
         |                           ^


vim +/buffer +598 drivers/iio/accel/kionix-kx022a.c

   593	
   594	static int __kx022a_fifo_flush(struct iio_dev *idev, unsigned int samples,
   595				       bool irq)
   596	{
   597		struct kx022a_data *data = iio_priv(idev);
 > 598		__le16 buffer[data->chip_info->fifo_length * 3];
   599		uint64_t sample_period;
   600		int count, fifo_bytes;
   601		bool renable = false;
   602		int64_t tstamp;
   603		int ret, i;
   604	
   605		fifo_bytes = kx022a_get_fifo_bytes(data);
   606		count = fifo_bytes / KX_FIFO_SAMPLES_SIZE_BYTES;
   607		if (!count)
   608			return 0;
   609	
   610		/*
   611		 * If we are being called from IRQ handler we know the stored timestamp
   612		 * is fairly accurate for the last stored sample. Otherwise, if we are
   613		 * called as a result of a read operation from userspace and hence
   614		 * before the watermark interrupt was triggered, take a timestamp
   615		 * now. We can fall anywhere in between two samples so the error in this
   616		 * case is at most one sample period.
   617		 */
   618		if (!irq) {
   619			/*
   620			 * We need to have the IRQ disabled or we risk of messing-up
   621			 * the timestamps. If we are ran from IRQ, then the
   622			 * IRQF_ONESHOT has us covered - but if we are ran by the
   623			 * user-space read we need to disable the IRQ to be on a safe
   624			 * side. We do this usng synchronous disable so that if the
   625			 * IRQ thread is being ran on other CPU we wait for it to be
   626			 * finished.
   627			 */
   628			disable_irq(data->irq);
   629			renable = true;
   630	
   631			data->old_timestamp = data->timestamp;
   632			data->timestamp = iio_get_time_ns(idev);
   633		}
   634	
   635		/*
   636		 * Approximate timestamps for each of the sample based on the sampling
   637		 * frequency, timestamp for last sample and number of samples.
   638		 *
   639		 * We'd better not use the current bandwidth settings to compute the
   640		 * sample period. The real sample rate varies with the device and
   641		 * small variation adds when we store a large number of samples.
   642		 *
   643		 * To avoid this issue we compute the actual sample period ourselves
   644		 * based on the timestamp delta between the last two flush operations.
   645		 */
   646		if (data->old_timestamp) {
   647			sample_period = data->timestamp - data->old_timestamp;
   648			do_div(sample_period, count);
   649		} else {
   650			sample_period = data->odr_ns;
   651		}
   652		tstamp = data->timestamp - (count - 1) * sample_period;
   653	
   654		if (samples && count > samples) {
   655			/*
   656			 * Here we leave some old samples to the buffer. We need to
   657			 * adjust the timestamp to match the first sample in the buffer
   658			 * or we will miscalculate the sample_period at next round.
   659			 */
   660			data->timestamp -= (count - samples) * sample_period;
   661			count = samples;
   662		}
   663	
   664		fifo_bytes = count * KX_FIFO_SAMPLES_SIZE_BYTES;
   665		ret = regmap_noinc_read(data->regmap, data->chip_info->buf_read,
   666					&buffer[0], fifo_bytes);
   667		if (ret)
   668			goto renable_out;
   669	
   670		for (i = 0; i < count; i++) {
   671			__le16 *sam = &buffer[i * 3];
   672			__le16 *chs;
   673			int bit;
   674	
   675			chs = &data->scan.channels[0];
   676			for_each_set_bit(bit, idev->active_scan_mask, AXIS_MAX)
   677				chs[bit] = sam[bit];
   678	
   679			iio_push_to_buffers_with_timestamp(idev, &data->scan, tstamp);
   680	
   681			tstamp += sample_period;
   682		}
   683	
   684		ret = count;
   685	
   686	renable_out:
   687		if (renable)
   688			enable_irq(data->irq);
   689	
   690		return ret;
   691	}
   692	

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