2024-01-07 01:28:59

by kernel test robot

[permalink] [raw]
Subject: drivers/iio/adc/axp20x_adc.c:572:26: sparse: sparse: dubious: x & !y

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 52b1853b080a082ec3749c3a9577f6c71b1d4a90
commit: 8957e5344353e9cd3f6b1e3004942e35449fa0e8 iio: adc: axp20x_adc: Minor code cleanups
date: 10 months ago
config: x86_64-randconfig-121-20240106 (https://download.01.org/0day-ci/archive/20240107/[email protected]/config)
compiler: ClangBuiltLinux clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240107/[email protected]/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 <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

sparse warnings: (new ones prefixed by >>)
>> drivers/iio/adc/axp20x_adc.c:572:26: sparse: sparse: dubious: x & !y
drivers/iio/adc/axp20x_adc.c:577:26: sparse: sparse: dubious: x & !y

vim +572 drivers/iio/adc/axp20x_adc.c

551
552 static int axp20x_write_raw(struct iio_dev *indio_dev,
553 struct iio_chan_spec const *chan, int val, int val2,
554 long mask)
555 {
556 struct axp20x_adc_iio *info = iio_priv(indio_dev);
557 unsigned int regmask, regval;
558
559 /*
560 * The AXP20X PMIC allows the user to choose between 0V and 0.7V offsets
561 * for (independently) GPIO0 and GPIO1 when in ADC mode.
562 */
563 if (mask != IIO_CHAN_INFO_OFFSET)
564 return -EINVAL;
565
566 if (val != 0 && val != 700000)
567 return -EINVAL;
568
569 switch (chan->channel) {
570 case AXP20X_GPIO0_V:
571 regmask = AXP20X_GPIO10_IN_RANGE_GPIO0;
> 572 regval = FIELD_PREP(AXP20X_GPIO10_IN_RANGE_GPIO0, !!val);
573 break;
574
575 case AXP20X_GPIO1_V:
576 regmask = AXP20X_GPIO10_IN_RANGE_GPIO1;
577 regval = FIELD_PREP(AXP20X_GPIO10_IN_RANGE_GPIO1, !!val);
578 break;
579
580 default:
581 return -EINVAL;
582 }
583
584 return regmap_update_bits(info->regmap, AXP20X_GPIO10_IN_RANGE, regmask, regval);
585 }
586

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki


2024-01-07 05:37:51

by Chen-Yu Tsai

[permalink] [raw]
Subject: Re: drivers/iio/adc/axp20x_adc.c:572:26: sparse: sparse: dubious: x & !y

On Sun, Jan 7, 2024 at 9:30 AM kernel test robot <[email protected]> wrote:
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 52b1853b080a082ec3749c3a9577f6c71b1d4a90
> commit: 8957e5344353e9cd3f6b1e3004942e35449fa0e8 iio: adc: axp20x_adc: Minor code cleanups
> date: 10 months ago
> config: x86_64-randconfig-121-20240106 (https://download.01.org/0day-ci/archive/20240107/[email protected]/config)
> compiler: ClangBuiltLinux clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240107/[email protected]/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 <[email protected]>
> | Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
>
> sparse warnings: (new ones prefixed by >>)
> >> drivers/iio/adc/axp20x_adc.c:572:26: sparse: sparse: dubious: x & !y
> drivers/iio/adc/axp20x_adc.c:577:26: sparse: sparse: dubious: x & !y

This looks like a false positive. The code is doing exactly what we want:
val = val ? 1 : 0, but in a shorter format.

ChenYu

>
> vim +572 drivers/iio/adc/axp20x_adc.c
>
> 551
> 552 static int axp20x_write_raw(struct iio_dev *indio_dev,
> 553 struct iio_chan_spec const *chan, int val, int val2,
> 554 long mask)
> 555 {
> 556 struct axp20x_adc_iio *info = iio_priv(indio_dev);
> 557 unsigned int regmask, regval;
> 558
> 559 /*
> 560 * The AXP20X PMIC allows the user to choose between 0V and 0.7V offsets
> 561 * for (independently) GPIO0 and GPIO1 when in ADC mode.
> 562 */
> 563 if (mask != IIO_CHAN_INFO_OFFSET)
> 564 return -EINVAL;
> 565
> 566 if (val != 0 && val != 700000)
> 567 return -EINVAL;
> 568
> 569 switch (chan->channel) {
> 570 case AXP20X_GPIO0_V:
> 571 regmask = AXP20X_GPIO10_IN_RANGE_GPIO0;
> > 572 regval = FIELD_PREP(AXP20X_GPIO10_IN_RANGE_GPIO0, !!val);
> 573 break;
> 574
> 575 case AXP20X_GPIO1_V:
> 576 regmask = AXP20X_GPIO10_IN_RANGE_GPIO1;
> 577 regval = FIELD_PREP(AXP20X_GPIO10_IN_RANGE_GPIO1, !!val);
> 578 break;
> 579
> 580 default:
> 581 return -EINVAL;
> 582 }
> 583
> 584 return regmap_update_bits(info->regmap, AXP20X_GPIO10_IN_RANGE, regmask, regval);
> 585 }
> 586
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki

2024-01-07 19:47:11

by Andy Shevchenko

[permalink] [raw]
Subject: Re: drivers/iio/adc/axp20x_adc.c:572:26: sparse: sparse: dubious: x & !y

On Sun, Jan 7, 2024 at 7:37 AM Chen-Yu Tsai <[email protected]> wrote:
> On Sun, Jan 7, 2024 at 9:30 AM kernel test robot <[email protected]> wrote:

...

> > sparse warnings: (new ones prefixed by >>)
> > >> drivers/iio/adc/axp20x_adc.c:572:26: sparse: sparse: dubious: x & !y
> > drivers/iio/adc/axp20x_adc.c:577:26: sparse: sparse: dubious: x & !y
>
> This looks like a false positive. The code is doing exactly what we want:
> val = val ? 1 : 0, but in a shorter format.

Yes, but the problem is that FIELD_PREP() is a macro.
You can replace these by ternary (here and in other cases) to satisfy
sparse. Compiler will optimize that anyway, so no branch is expected
in the generated code.

--
With Best Regards,
Andy Shevchenko