Re: [PATCH 1/2] iio: adc: ad4695: implement triggered buffer

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

Hi David,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 7cad163c39cb642ed587d3eeb37a5637ee02740f]

url:    https://github.com/intel-lab-lkp/linux/commits/David-Lechner/iio-adc-ad4695-implement-triggered-buffer/20240808-063333
base:   7cad163c39cb642ed587d3eeb37a5637ee02740f
patch link:    https://lore.kernel.org/r/20240807-iio-adc-ad4695-buffered-read-v1-1-bdafc39b2283%40baylibre.com
patch subject: [PATCH 1/2] iio: adc: ad4695: implement triggered buffer
config: hexagon-allmodconfig (https://download.01.org/0day-ci/archive/20240808/202408081623.ua9EBfoZ-lkp@intel.com/config)
compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project 408d82d352eb98e2d0a804c66d359cd7a49228fe)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240808/202408081623.ua9EBfoZ-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/202408081623.ua9EBfoZ-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from drivers/iio/adc/ad4695.c:24:
   In file included from include/linux/iio/triggered_buffer.h:6:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:14:
   In file included from arch/hexagon/include/asm/io.h:328:
   include/asm-generic/io.h:548:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     548 |         val = __raw_readb(PCI_IOBASE + addr);
         |                           ~~~~~~~~~~ ^
   include/asm-generic/io.h:561:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     561 |         val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
         |                                                         ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
      37 | #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
         |                                                   ^
   In file included from drivers/iio/adc/ad4695.c:24:
   In file included from include/linux/iio/triggered_buffer.h:6:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:14:
   In file included from arch/hexagon/include/asm/io.h:328:
   include/asm-generic/io.h:574:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     574 |         val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
         |                                                         ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
      35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
         |                                                   ^
   In file included from drivers/iio/adc/ad4695.c:24:
   In file included from include/linux/iio/triggered_buffer.h:6:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:14:
   In file included from arch/hexagon/include/asm/io.h:328:
   include/asm-generic/io.h:585:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     585 |         __raw_writeb(value, PCI_IOBASE + addr);
         |                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:595:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     595 |         __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
         |                                                       ~~~~~~~~~~ ^
   include/asm-generic/io.h:605:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     605 |         __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
         |                                                       ~~~~~~~~~~ ^
   In file included from drivers/iio/adc/ad4695.c:28:
   In file included from include/linux/regulator/consumer.h:35:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:21:
   In file included from include/linux/mm.h:2228:
   include/linux/vmstat.h:514:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
     514 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
         |                               ~~~~~~~~~~~ ^ ~~~
>> drivers/iio/adc/ad4695.c:454:8: warning: result of comparison of constant 18446744073709551615 with expression of type 'typeof (_Generic((mask), char: (unsigned char)0, unsigned char: (unsigned char)0, signed char: (unsigned char)0, unsigned short: (unsigned short)0, short: (unsigned short)0, unsigned int: (unsigned int)0, int: (unsigned int)0, unsigned long: (unsigned long)0, long: (unsigned long)0, unsigned long long: (unsigned long long)0, long long: (unsigned long long)0, default: (mask)))' (aka 'unsigned int') is always false [-Wtautological-constant-out-of-range-compare]
     454 |         val = FIELD_PREP(mask, temp_chan_en ? 1 : 0);
         |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/bitfield.h:115:3: note: expanded from macro 'FIELD_PREP'
     115 |                 __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: ");    \
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/bitfield.h:72:53: note: expanded from macro '__BF_FIELD_CHECK'
      72 |                 BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) >     \
         |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
      73 |                                  __bf_cast_unsigned(_reg, ~0ull),       \
         |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      74 |                                  _pfx "type of reg too small for mask"); \
         |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:39:58: note: expanded from macro 'BUILD_BUG_ON_MSG'
      39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
         |                                     ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
   include/linux/compiler_types.h:510:22: note: expanded from macro 'compiletime_assert'
     510 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
         |         ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler_types.h:498:23: note: expanded from macro '_compiletime_assert'
     498 |         __compiletime_assert(condition, msg, prefix, suffix)
         |         ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler_types.h:490:9: note: expanded from macro '__compiletime_assert'
     490 |                 if (!(condition))                                       \
         |                       ^~~~~~~~~
   8 warnings generated.


vim +454 drivers/iio/adc/ad4695.c

   373	
   374	static int ad4695_buffer_preenable(struct iio_dev *indio_dev)
   375	{
   376		struct ad4695_state *st = iio_priv(indio_dev);
   377		struct spi_transfer *xfer;
   378		u8 temp_chan_bit = st->chip_info->num_voltage_inputs;
   379		bool temp_chan_en = false;
   380		u32 reg, mask, val, bit, num_xfer, num_slots;
   381		int ret;
   382	
   383		/*
   384		 * We are using the advanced sequencer since it is the only way to read
   385		 * multiple channels that allows individual configuration of each
   386		 * voltage input channel. Slot 0 in the advanced sequencer is used to
   387		 * account for the gap between trigger polls - we don't read data from
   388		 * this slot. Each enabled voltage channel is assigned a slot starting
   389		 * with slot 1.
   390		 */
   391		num_slots = 1;
   392	
   393		memset(st->buf_read_xfer, 0, sizeof(st->buf_read_xfer));
   394	
   395		/* First xfer is only to trigger conversion of slot 1, so no rx. */
   396		xfer = &st->buf_read_xfer[0];
   397		xfer->cs_change = 1;
   398		xfer->delay.value = AD4695_T_CNVL_NS;
   399		xfer->delay.unit = SPI_DELAY_UNIT_NSECS;
   400		xfer->cs_change_delay.value = AD4695_T_CONVERT_NS;
   401		xfer->cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
   402		num_xfer = 1;
   403	
   404		iio_for_each_active_channel(indio_dev, bit) {
   405			xfer = &st->buf_read_xfer[num_xfer];
   406			xfer->bits_per_word = 16;
   407			xfer->rx_buf = &st->buf[(num_xfer - 1) * 2];
   408			xfer->len = 2;
   409			xfer->cs_change = 1;
   410			xfer->cs_change_delay.value = AD4695_T_CONVERT_NS;
   411			xfer->cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
   412	
   413			if (bit == temp_chan_bit) {
   414				temp_chan_en = true;
   415			} else {
   416				reg = AD4695_REG_AS_SLOT(num_slots);
   417				val = FIELD_PREP(AD4695_REG_AS_SLOT_INX, bit);
   418	
   419				ret = regmap_write(st->regmap, reg, val);
   420				if (ret)
   421					return ret;
   422	
   423				num_slots++;
   424			}
   425	
   426			num_xfer++;
   427		}
   428	
   429		/*
   430		 * Don't keep CS asserted after last xfer. Also triggers conversion of
   431		 * slot 0.
   432		 */
   433		xfer->cs_change = 0;
   434	
   435		/**
   436		 * The advanced sequencer requires that at least 2 slots are enabled.
   437		 * Since slot 0 is always used for other purposes, we need only 1
   438		 * enabled voltage channel to meet this requirement. This error will
   439		 * only happen if only the temperature channel is enabled.
   440		 */
   441		if (num_slots < 2) {
   442			dev_err_ratelimited(&indio_dev->dev,
   443				"Buffered read requires at least 1 voltage channel enabled\n");
   444			return -EINVAL;
   445		}
   446	
   447		/*
   448		 * Temperature channel isn't included in the sequence, but rather
   449		 * controlled by setting a bit in the TEMP_CTRL register.
   450		 */
   451	
   452		reg = AD4695_REG_TEMP_CTRL;
   453		mask = AD4695_REG_TEMP_CTRL_TEMP_EN;
 > 454		val = FIELD_PREP(mask, temp_chan_en ? 1 : 0);
   455	
   456		ret = regmap_update_bits(st->regmap, reg, mask, val);
   457		if (ret)
   458			return ret;
   459	
   460		spi_message_init_with_transfers(&st->buf_read_msg, st->buf_read_xfer,
   461						num_xfer);
   462	
   463		ret = spi_optimize_message(st->spi, &st->buf_read_msg);
   464		if (ret)
   465			return ret;
   466	
   467		/* This triggers conversion of slot 0. */
   468		ret = ad4695_enter_advanced_sequencer_mode(st, num_slots);
   469		if (ret) {
   470			spi_unoptimize_message(&st->buf_read_msg);
   471			return ret;
   472		}
   473	
   474		return 0;
   475	}
   476	

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