linux-kernel - Re: [PATCH] iio: dac: max5821: convert device register to device managed function

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Date:   Mon, 19 Jul 2021 10:32:54 +0300
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Théo Borém Fabris <theobf@....br>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        linux-iio <linux-iio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: dac: max5821: convert device register to device
 managed function

On Sun, Jul 18, 2021 at 11:42 PM Théo Borém Fabris <theobf@....br> wrote:
>
> Add a device managed hook, via devm_add_action_or_reset() and
> max5821_regulator_disable(), to disable voltage regulator on device
> detach.
> Replace iio_device_register() by devm_iio_device_register() and remove
> the max5821_remove() function used to unregister the device and disable the
> voltage regulator.
> Remove i2c_set_clientdata() from the probe function, since
> i2c_get_clientdata() is not used anymore.

Looks good overall.
A few comments inline.

>
> Signed-off-by: Théo Borém Fabris <theobf@....br>
> ---
>  drivers/iio/dac/max5821.c | 30 ++++++++++++++++--------------
>  1 file changed, 16 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/iio/dac/max5821.c b/drivers/iio/dac/max5821.c
> index bd6e75699a63..44c04ae70b32 100644
> --- a/drivers/iio/dac/max5821.c
> +++ b/drivers/iio/dac/max5821.c
> @@ -294,6 +294,13 @@ static const struct iio_info max5821_info = {
>         .write_raw = max5821_write_raw,
>  };
>
> +static void max5821_regulator_disable(void *data)
> +{
> +       struct regulator *rdata = data;
> +
> +       regulator_disable(rdata);

This can be simplified a bit:

static void max5821_regulator_disable(void *reg)
{
      regulator_disable(reg);
}

I used to do explicit casting, but then I also figured that it's not necessary.

> +}
> +
>  static int max5821_probe(struct i2c_client *client,
>                         const struct i2c_device_id *id)
>  {
> @@ -306,7 +313,6 @@ static int max5821_probe(struct i2c_client *client,
>         if (!indio_dev)
>                 return -ENOMEM;
>         data = iio_priv(indio_dev);
> -       i2c_set_clientdata(client, indio_dev);
>         data->client = client;
>         mutex_init(&data->lock);
>
> @@ -331,6 +337,14 @@ static int max5821_probe(struct i2c_client *client,
>                 goto error_free_reg;
>         }
>
> +       ret = devm_add_action_or_reset(&client->dev, max5821_regulator_disable,
> +                                      data->vref_reg);
> +       if (ret) {
> +               dev_err(&client->dev,
> +                       "Failed to add action to managed regulator: %d\n", ret);
> +               goto error_disable_reg;

return ret;

devm_add_action_or_reset() should call max5821_regulator_disable() in
case of error

> +       }
> +
>         ret = regulator_get_voltage(data->vref_reg);
>         if (ret < 0) {
>                 dev_err(&client->dev,
> @@ -346,7 +360,7 @@ static int max5821_probe(struct i2c_client *client,
>         indio_dev->modes = INDIO_DIRECT_MODE;
>         indio_dev->info = &max5821_info;
>
> -       return iio_device_register(indio_dev);
> +       return devm_iio_device_register(&client->dev, indio_dev);
>
>  error_disable_reg:

This entire goto block should be removed.
The idea of using only devm_ functions is to not have these goto statements.

>         regulator_disable(data->vref_reg);
> @@ -356,17 +370,6 @@ static int max5821_probe(struct i2c_client *client,
>         return ret;
>  }
>
> -static int max5821_remove(struct i2c_client *client)
> -{
> -       struct iio_dev *indio_dev = i2c_get_clientdata(client);
> -       struct max5821_data *data = iio_priv(indio_dev);
> -
> -       iio_device_unregister(indio_dev);
> -       regulator_disable(data->vref_reg);
> -
> -       return 0;
> -}
> -
>  static const struct i2c_device_id max5821_id[] = {
>         { "max5821", ID_MAX5821 },
>         { }
> @@ -386,7 +389,6 @@ static struct i2c_driver max5821_driver = {
>                 .pm     = &max5821_pm_ops,
>         },
>         .probe          = max5821_probe,
> -       .remove         = max5821_remove,
>         .id_table       = max5821_id,
>  };
>  module_i2c_driver(max5821_driver);
> --
> 2.20.1
>