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

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Date:   Wed, 1 Jul 2020 01:11:16 +0900
From:   Sungbo Eo <mans0n@...ani.run>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     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

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?

Thanks.

On 2020-06-30 18:53, Andy Shevchenko wrote:
> On Tue, Jun 30, 2020 at 12:28 PM Bartosz Golaszewski
> <bgolaszewski@...libre.com> wrote:
>> On Thu, Jun 25, 2020 at 9:58 AM Sungbo Eo <mans0n@...ani.run> wrote:
> 
>>> +static const struct of_device_id pca9570_of_match_table[] = {
>>> +       { .compatible = "nxp,pca9570" },
>>> +       { /* sentinel */ }
>>> +};
>>> +MODULE_DEVICE_TABLE(of, pca9570_of_match_table);
>>
>> If you're not using it in probe than maybe move it next to the I2C device table?
> 
> (Side note)
> ...and even if so it can be assessed via a struct device pointer:
> dev->driver->id_table (don't remember by heart, but you have an idea).
>