linux-kernel - Re: [PATCH v2 1/2] gpio: add GPO driver for PCA9570

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Message-ID: <CAHp75VcA-kmJHyuZOMs-BDqhQ7FszZti=uHmSs-NCH2F6e_c4A@mail.gmail.com>
Date:   Wed, 1 Jul 2020 00:23:48 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Sungbo Eo <mans0n@...ani.run>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-gpio <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] gpio: add GPO driver for PCA9570

On Tue, Jun 30, 2020 at 7:11 PM Sungbo Eo <mans0n@...ani.run> wrote:
>
> Thanks for all the reviews! I've updated the patch, please have a look.
>
> And I have something to ask.
>
> # echo 1 > gpio408/value
> # cat gpio408/value
> cat: read error: I/O error
> # cat gpio408/direction
> out
> # echo out > gpio408/direction
> # echo in > gpio408/direction
> [   91.006691] gpio-408 (sysfs): gpiod_direction_input: missing get()
> but have direction_input()
> ash: write error: I/O error
>
> I've never dealt with GPO expander before, so this seems a bit odd to me.
> Is it perfectly okay to leave get() and direction_input() unimplemented?

Actually it would be better to return the value you set for output in ->get().


-- 
With Best Regards,
Andy Shevchenko