Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values

From	Jan Kiszka <jan.kiszka@siemens.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values
Date	2017-05-18 12:20 +0200
Message-ID	<tIqHf-TR-7@gated-at.bofh.it> (permalink)
References	<tGzF0-rm-5@gated-at.bofh.it> <tGzOF-uC-3@gated-at.bofh.it> <tGFr4-4gr-13@gated-at.bofh.it> <tImaB-5sL-3@gated-at.bofh.it> <tIqHf-TR-9@gated-at.bofh.it>
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On 2017-05-18 12:11, Andy Shevchenko wrote:
> On Thu, May 18, 2017 at 8:20 AM, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>> On 2017-05-13 15:36, Andy Shevchenko wrote:
>>> On Sat, May 13, 2017 at 10:29 AM, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>>> First, the logic for translating a register bit to the return code of
>>>> exar_get_direction and exar_get_value were wrong. And second, there was
>>>> a flip regarding the register bank in exar_get_direction.
>>>
>>> Again, I wish it was tested in the first place.
>>>
>>> After addressing below:
>>> FWIW:
>>> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
>>>
>>>> @@ -68,7 +68,7 @@ static int exar_get(struct gpio_chip *chip, unsigned int reg)
>>>>         value = readb(exar_gpio->regs + reg);
>>>>         mutex_unlock(&exar_gpio->lock);
>>>>
>>>> -       return !!value;
>>>> +       return value;
>>>
>>> This one is correct.
> 
>>>
>>>> @@ -80,7 +80,7 @@ static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
>>>>         addr = bank ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
>>>>         val = exar_get(chip, addr) >> (offset % 8);
>>>>
>>>> -       return !!val;
>>>> +       return val & 1;
>>>
>>> It should be rather
>>>
>>>         val = exar_get(chip, addr) & BIT(offset % 8);
>>
>> That won't give us 0 or 1 as return value, thus would be incorrect.
> 
> Full picture:
> 
>  val = exar_get(chip, addr) & BIT(offset % 8);
> 
>  return !!val;
> 
> How it could be non-(1 or 0)?
> 

Right - but what is the point of that other style?

Jan

-- 
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Corporate Competence Center Embedded Linux

Thread

[PATCH 0/8] serial/gpio: exar: Fixes and support for IOT2000 Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-13 09:40 +0200
  [PATCH 5/8] gpio: exar: Fix reading of directions and values Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-13 09:40 +0200
    Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-05-13 15:40 +0200
      Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-18 07:30 +0200
        Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-18 12:20 +0200
          Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-18 12:30 +0200
          Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-05-18 12:30 +0200
        Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-05-18 12:20 +0200
  [PATCH 7/8] gpio-exar/8250-exar: Make set of exported GPIOs configurable Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-13 09:40 +0200
    Re: [PATCH 7/8] gpio-exar/8250-exar: Make set of exported GPIOs configurable Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-05-13 16:00 +0200
  [PATCH 1/8] serial: exar: Preconfigure xr17v35x MPIOs as output Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-13 09:40 +0200
    Re: [PATCH 1/8] serial: exar: Preconfigure xr17v35x MPIOs as output Linus Walleij <linus.walleij@linaro.org> - 2017-05-22 17:50 +0200
  [PATCH 3/8] gpio: exar: Allocate resources on behalf of the platform device Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-13 09:40 +0200
    Re: [PATCH 3/8] gpio: exar: Allocate resources on behalf of the  platform device Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-05-13 15:30 +0200
    Re: [PATCH 3/8] gpio: exar: Allocate resources on behalf of the  platform device Linus Walleij <linus.walleij@linaro.org> - 2017-05-22 17:50 +0200
  [PATCH 6/8] serial: uapi: Add support for bus termination Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-13 09:40 +0200

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