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Message-ID: <20240810102021.45b35e59@jic23-huawei>
Date: Sat, 10 Aug 2024 10:20:21 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: kernel test robot <lkp@...el.com>
Cc: David Lechner <dlechner@...libre.com>, llvm@...ts.linux.dev,
oe-kbuild-all@...ts.linux.dev, Michael Hennerich
<Michael.Hennerich@...log.com>, Nuno Sá <nuno.sa@...log.com>,
Jonathan Corbet <corbet@....net>, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH 1/2] iio: adc: ad4695: implement triggered buffer
On Thu, 8 Aug 2024 16:52:09 +0800
kernel test robot <lkp@...el.com> wrote:
> 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@...el.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);
Probably a case of the compiler somehow failing to squash the local variable.
I'd just go with
val = FIELD_PREP(AD4695_REG_TEMP_CTRL_TEMP_EN,
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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