Re: [PATCH v3 1/8] iio: stx104: Implement get_multiple callback

[William Breathitt Gray]

On Sat, Mar 17, 2018 at 08:51:07PM +0200, Andy Shevchenko wrote:
>On Sat, Mar 17, 2018 at 5:49 PM, William Breathitt Gray
><vilhelm.gray@xxxxxxxxx> wrote:
>> The Apex Embedded Systems STX104 series of devices provides 4 TTL
>> compatible lines of inputs accessed via a single 4-bit port. Since four
>> input lines are acquired on a single port input read, the STX104 GPIO
>> driver may improve multiple input reads by utilizing a get_multiple
>> callback. This patch implements the stx104_gpio_get_multiple function
>> which serves as the respective get_multiple callback.
>
>> +static int stx104_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
>> +       unsigned long *bits)
>> +{
>> +       struct stx104_gpio *const stx104gpio = gpiochip_get_data(chip);
>> +
>
>> +       *bits = inb(stx104gpio->base);
>
>I think on LE and BE if will give you different results.

That may be true for a memcpy operation, but in this case I'm relying on
the standard C evaluation rules. I expect we should be fine with the
returned byte assigned to an unsigned long, since it'll be evaluated by
its value rather than memory representation.

William Breathitt Gray

>
>> +
>> +       return 0;
>> +}
>
>
>
>-- 
>With Best Regards,
>Andy Shevchenko