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

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