linux-kernel - Re: [PATCH] iio:dac:max517: Use devm_iio_device

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Message-ID: <CA+U=DspBephozOheNQYBX9jG6bdwm4FeOTF_9tEggOWNvTQ32Q@mail.gmail.com>
Date:   Sun, 14 Mar 2021 13:07:52 +0200
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Mugilraj Dhavachelvan <dmugil2000@...il.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio <linux-iio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio:dac:max517: Use devm_iio_device_register()

On Sun, Mar 14, 2021 at 11:34 AM Mugilraj Dhavachelvan
<dmugil2000@...il.com> wrote:
>
> Use devm_iio_device_register() to avoid remove function and
> drop explicit call to iio_device_unregister().
>
> Signed-off-by: Mugilraj Dhavachelvan <dmugil2000@...il.com>
> ---
>  drivers/iio/dac/max517.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/drivers/iio/dac/max517.c b/drivers/iio/dac/max517.c
> index 7e01838ef4d0..5f72f126162d 100644
> --- a/drivers/iio/dac/max517.c
> +++ b/drivers/iio/dac/max517.c
> @@ -189,13 +189,7 @@ static int max517_probe(struct i2c_client *client,
>                         data->vref_mv[chan] = platform_data->vref_mv[chan];
>         }
>
> -       return iio_device_register(indio_dev);
> -}
> -

In this case you can also remove the line with
     i2c_set_clientdata(client, indio_dev);

A lot of times, when functions like i2c_get_clientdata() get removed,
the i2c_set_clientdata() function becomes useless.
i.e. it stores some data that will never be used in the lifetime of the driver.

It isn't always the case that you can do that; so, some care must be
taken to avoid special cases.
But in this case, you can remove the i2c_set_clientdata() call.


> -static int max517_remove(struct i2c_client *client)
> -{
> -       iio_device_unregister(i2c_get_clientdata(client));
> -       return 0;
> +       return devm_iio_device_register(&client->dev, indio_dev);
>  }
>
>  static const struct i2c_device_id max517_id[] = {
> @@ -214,7 +208,6 @@ static struct i2c_driver max517_driver = {
>                 .pm     = &max517_pm_ops,
>         },
>         .probe          = max517_probe,
> -       .remove         = max517_remove,
>         .id_table       = max517_id,
>  };
>  module_i2c_driver(max517_driver);
> --
> 2.25.1
>