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Date: Sat, 24 Dec 2022 17:19:27 +0100 From: Andy Shevchenko <andy.shevchenko@...il.com> To: Dan Carpenter <error27@...il.com> Cc: oe-kbuild@...ts.linux.dev, Qingtao Cao <qingtao.cao.au@...il.com>, lkp@...el.com, oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org, Bartosz Golaszewski <brgl@...ev.pl> Subject: Re: drivers/gpio/gpio-exar.c:52 exar_offset_to_sel_addr() warn: replace divide condition 'pin / 8' with 'pin >= 8' Lähetetty iPhonesta > Dan Carpenter <error27@...il.com> kirjoitti 23.12.2022 kello 11.54: > > 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' > I don’t think this is a good advice. If we want to limit that, we need to check also upper limit. But. The GPIO framework does that. So, changing / to >= is bogus. > 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 } > > -- > 0-DAY CI Kernel Test Service > https://01.org/lkp >
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