Re: [PATCH 2/4] gpio: Introduce ->get_multiple callback

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Thu, Aug 31, 2017 at 5:46 PM, Lukas Wunner <lukas@xxxxxxxxx> wrote:
> On Thu, Aug 31, 2017 at 03:48:15PM +0200, Linus Walleij wrote:
>> On Sun, Aug 27, 2017 at 7:34 PM, Lukas Wunner <lukas@xxxxxxxxx> wrote:
>> > At least with SPI-attached GPIO controllers, the transmission is never
>> > guaranteed to succeed, so errors can occur both for input and output
>> > GPIOs.  The MAX3191x is input-only and does pass SPI errors back to
>> > the caller.  Output drivers such as gpio-74x164.c silently ignore
>> > SPI errors, which is arguably a problem.
>>
>> This has historical reasons.
>
> Would you generally be open for allowing errors to be returned from
> the set functions as well?

Yes if we can make a series fixing the fallout.

>  The Revolution Pi uses SPI-attached
> digital outputs and knowing if access to them fails would be useful.

True.

> For consumers, switching the return value from void to int shouldn't
> cause any fallout.  They just don't check the return value initially.

Indeed.

> However the ->set and ->set_multiple callbacks in all the GPIO drivers
> would need to be changed, that's where the real work is.

Yeah :/

But there are not so many of them, luckily.

Yours,
Linus Walleij
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