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

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Date:   Thu, 18 May 2017 07:20:23 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>,
        Sascha Weisenberger <sascha.weisenberger@...mens.com>
Subject: Re: [PATCH 5/8] gpio: exar: Fix reading of directions and values

On 2017-05-13 15:36, Andy Shevchenko wrote:
> On Sat, May 13, 2017 at 10:29 AM, Jan Kiszka <jan.kiszka@...mens.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@...il.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.

> 
>>  }
>>
>>  static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
>> @@ -89,10 +89,10 @@ static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
>>         unsigned int addr;
>>         int val;
>>
>> -       addr = bank ? EXAR_OFFSET_MPIOLVL_LO : EXAR_OFFSET_MPIOLVL_HI;
>> +       addr = bank ? EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
> 
> Good catch!
> 
>>         val = exar_get(chip, addr) >> (offset % 8);
>>
>> -       return !!val;
>> +       return val & 1;
> 
> Ditto (see above).
> 

Same here.

Jan

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