linux-kernel - drivers/gpio/gpio-exar.c:52 exar_offset_to_sel_addr() warn: replace divide condition 'pin / 8' with 'pin >= 8'

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Date:   Fri, 23 Dec 2022 13:54:37 +0300
From:   Dan Carpenter <error27@...il.com>
To:     oe-kbuild@...ts.linux.dev, Qingtao Cao <qingtao.cao.au@...il.com>
Cc:     lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
        linux-kernel@...r.kernel.org, Bartosz Golaszewski <brgl@...ev.pl>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Subject: drivers/gpio/gpio-exar.c:52 exar_offset_to_sel_addr() warn: replace
 divide condition 'pin / 8' with 'pin >= 8'

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   f9ff5644bcc04221bae56f922122f2b7f5d24d62
commit: 5134272f9f3f71d4e1f3aa15cb09321af49b3646 gpio: exar: access MPIO registers on cascaded chips
config: ia64-randconfig-m031-20221218
compiler: ia64-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
| Reported-by: Dan Carpenter <error27@...il.com>

smatch warnings:
drivers/gpio/gpio-exar.c:52 exar_offset_to_sel_addr() warn: replace divide condition 'pin / 8' with 'pin >= 8'
drivers/gpio/gpio-exar.c:62 exar_offset_to_lvl_addr() warn: replace divide condition 'pin / 8' with 'pin >= 8'

vim +52 drivers/gpio/gpio-exar.c

696868d0a79c21 Bartosz Golaszewski 2020-09-30  47  static unsigned int
696868d0a79c21 Bartosz Golaszewski 2020-09-30  48  exar_offset_to_sel_addr(struct exar_gpio_chip *exar_gpio, unsigned int offset)
696868d0a79c21 Bartosz Golaszewski 2020-09-30  49  {
5134272f9f3f71 Qingtao Cao         2022-09-02  50  	unsigned int pin = exar_gpio->first_pin + (offset % 16);
5134272f9f3f71 Qingtao Cao         2022-09-02  51  	unsigned int cascaded = offset / 16;
5134272f9f3f71 Qingtao Cao         2022-09-02 @52  	unsigned int addr = pin / 8 ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;

Why not change this to pin > 8 instead.  Comparisons are faster than
divide ops.  Way more readable too.

5134272f9f3f71 Qingtao Cao         2022-09-02  53  
5134272f9f3f71 Qingtao Cao         2022-09-02  54  	return addr + (cascaded ? exar_gpio->cascaded_offset : 0);
696868d0a79c21 Bartosz Golaszewski 2020-09-30  55  }
696868d0a79c21 Bartosz Golaszewski 2020-09-30  56  
696868d0a79c21 Bartosz Golaszewski 2020-09-30  57  static unsigned int
696868d0a79c21 Bartosz Golaszewski 2020-09-30  58  exar_offset_to_lvl_addr(struct exar_gpio_chip *exar_gpio, unsigned int offset)
696868d0a79c21 Bartosz Golaszewski 2020-09-30  59  {
5134272f9f3f71 Qingtao Cao         2022-09-02  60  	unsigned int pin = exar_gpio->first_pin + (offset % 16);
5134272f9f3f71 Qingtao Cao         2022-09-02  61  	unsigned int cascaded = offset / 16;
5134272f9f3f71 Qingtao Cao         2022-09-02 @62  	unsigned int addr = pin / 8 ? EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
5134272f9f3f71 Qingtao Cao         2022-09-02  63  
5134272f9f3f71 Qingtao Cao         2022-09-02  64  	return addr + (cascaded ? exar_gpio->cascaded_offset : 0);
696868d0a79c21 Bartosz Golaszewski 2020-09-30  65  }

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