[PATCH] iio: dac: max5821: convert device register to device managed function

[PATCH] iio: dac: max5821: convert device register to device managed function

[Théo Borém Fabris]

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.

Signed-off-by: Théo Borém Fabris <theobf@usp.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);
+}
+
 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;
+	}
+
 	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:
 	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

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

[Alexandru Ardelean]

On Sun, Jul 18, 2021 at 11:42 PM Théo Borém Fabris <theobf@usp.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@usp.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
>

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

[Théo Borém Fabris]

Hi, Alexandru.

Em seg., 19 de jul. de 2021 às 04:33, Alexandru Ardelean
<ardeleanalex@gmail.com> escreveu:
>
> On Sun, Jul 18, 2021 at 11:42 PM Théo Borém Fabris <theobf@usp.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@usp.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.
>
Ok.

> > +}
> > +
> >  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
>
Ok.

> > +       }
> > +
> >         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.
>
I thought the action added via devm_add_action (and devres_add) was called only
on driver detach, thus the error_disable_reg label would be necessary
to handle the
possible error on regulator_get_voltage. Could you please clarify for
me when does
a driver detach happen?

Thanks for your reply,
Théo

> >         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
> >

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

[Alexandru Ardelean]

On Mon, Jul 19, 2021 at 6:25 PM Théo Borém Fabris <theobf@usp.br> wrote:
>
> Hi, Alexandru.
>
> Em seg., 19 de jul. de 2021 às 04:33, Alexandru Ardelean
> <ardeleanalex@gmail.com> escreveu:
> >
> > On Sun, Jul 18, 2021 at 11:42 PM Théo Borém Fabris <theobf@usp.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@usp.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.
> >
> Ok.
>
> > > +}
> > > +
> > >  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
> >
> Ok.
>
> > > +       }
> > > +
> > >         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.
> >
> I thought the action added via devm_add_action (and devres_add) was called only
> on driver detach, thus the error_disable_reg label would be necessary
> to handle the

devm_add_action() yes
this is devm_add_action_or_reset() which looks like this:

static inline int devm_add_action_or_reset(struct device *dev,
                       void (*action)(void *), void *data)
{
    int ret;

    ret = devm_add_action(dev, action, data);
    if (ret)
        action(data);

    return ret;
}

it can be found in "include/linux/device.h"

> possible error on regulator_get_voltage. Could you please clarify for
> me when does
> a driver detach happen?

a driver detach happens when:
* the kmod is unloaded (assuming the driver is running as a kmod)
* manually unbinding the driver from sysfs ;
   a quick article about this [it's for USB, but other interfaces use
   the same mechanism]:
   https://lwn.net/Articles/143397/
   there should be something under /sys/bus/spi/drivers/xxxx/unbind
* when the system powers down (reboots)
* maybe there is some other new method to do this [that I don't know about]

>
> Thanks for your reply,
> Théo
>
> > >         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
> > >

RE: [PATCH] iio: dac: max5821: convert device register to device managed function

[Sa, Nuno]

> From: Alexandru Ardelean <ardeleanalex@gmail.com>
> Sent: Tuesday, July 20, 2021 9:23 AM
> To: Théo Borém Fabris <theobf@usp.br>
> Cc: Jonathan Cameron <jic23@kernel.org>; Lars-Peter Clausen
> <lars@metafoo.de>; linux-iio <linux-iio@vger.kernel.org>; LKML
> <linux-kernel@vger.kernel.org>
> Subject: Re: [PATCH] iio: dac: max5821: convert device register to
> device managed function
> 
> On Mon, Jul 19, 2021 at 6:25 PM Théo Borém Fabris <theobf@usp.br>
> wrote:
> >
> > Hi, Alexandru.
> >
> > Em seg., 19 de jul. de 2021 às 04:33, Alexandru Ardelean
> > <ardeleanalex@gmail.com> escreveu:
> > >
> > > On Sun, Jul 18, 2021 at 11:42 PM Théo Borém Fabris
> <theobf@usp.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@usp.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.
> > >
> > Ok.
> >
> > > > +}
> > > > +
> > > >  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
> > >
> > Ok.
> >
> > > > +       }
> > > > +
> > > >         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.
> > >
> > I thought the action added via devm_add_action (and devres_add)
> was called only
> > on driver detach, thus the error_disable_reg label would be
> necessary
> > to handle the
> 
> devm_add_action() yes
> this is devm_add_action_or_reset() which looks like this:
> 
> static inline int devm_add_action_or_reset(struct device *dev,
>                        void (*action)(void *), void *data)
> {
>     int ret;
> 
>     ret = devm_add_action(dev, action, data);
>     if (ret)
>         action(data);
> 
>     return ret;
> }
> 
> it can be found in "include/linux/device.h"
> 
> > possible error on regulator_get_voltage. Could you please clarify for
> > me when does
> > a driver detach happen?
> 
> a driver detach happens when:
> * the kmod is unloaded (assuming the driver is running as a kmod)
> * manually unbinding the driver from sysfs ;
>    a quick article about this [it's for USB, but other interfaces use
>    the same mechanism]:
> 
> https://urldefense.com/v3/__https://lwn.net/Articles/143397/__;!!A
> 3Ni8CS0y2Y!rw-
> qxijVlohZWCG9q_wWFPGASqW7JWcfS48uJSwY8coKiBPoA9Z0G2WSCZ
> clCw$
>    there should be something under /sys/bus/spi/drivers/xxxx/unbind
> * when the system powers down (reboots)
> * maybe there is some other new method to do this [that I don't know
> about]

If the device get's deleted with 'device_del()'...

- Nuno Sá

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

[Théo Borém Fabris]

Em ter., 20 de jul. de 2021 às 04:22, Alexandru Ardelean
<ardeleanalex@gmail.com> escreveu:
>
> On Mon, Jul 19, 2021 at 6:25 PM Théo Borém Fabris <theobf@usp.br> wrote:
> >
> > Hi, Alexandru.
> >
> > Em seg., 19 de jul. de 2021 às 04:33, Alexandru Ardelean
> > <ardeleanalex@gmail.com> escreveu:
> > >
> > > On Sun, Jul 18, 2021 at 11:42 PM Théo Borém Fabris <theobf@usp.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@usp.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.
> > >
> > Ok.
> >
> > > > +}
> > > > +
> > > >  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
> > >
> > Ok.
> >
> > > > +       }
> > > > +
> > > >         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.
> > >
> > I thought the action added via devm_add_action (and devres_add) was called only
> > on driver detach, thus the error_disable_reg label would be necessary
> > to handle the
>
> devm_add_action() yes
> this is devm_add_action_or_reset() which looks like this:
>
> static inline int devm_add_action_or_reset(struct device *dev,
>                        void (*action)(void *), void *data)
> {
>     int ret;
>
>     ret = devm_add_action(dev, action, data);
>     if (ret)
>         action(data);
>
>     return ret;
> }
>
> it can be found in "include/linux/device.h"
>
> > possible error on regulator_get_voltage. Could you please clarify for
> > me when does
> > a driver detach happen?
>
> a driver detach happens when:
> * the kmod is unloaded (assuming the driver is running as a kmod)
> * manually unbinding the driver from sysfs ;
>    a quick article about this [it's for USB, but other interfaces use
>    the same mechanism]:
>    https://lwn.net/Articles/143397/
>    there should be something under /sys/bus/spi/drivers/xxxx/unbind
> * when the system powers down (reboots)
> * maybe there is some other new method to do this [that I don't know about]
>
Thank you so much.

So, should this goto error_disable_reg be replaced by
"regulator_disable(.); return ret;"?
ret = regulator_get_voltage(data->vref_reg);
    if (ret < 0) {
        dev_err(&client->dev,
             "Failed to get voltage on regulator: %d\n", ret);
        goto error_disable_reg;
    }

> >
> > Thanks for your reply,
> > Théo
> >
> > > >         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
> > > >

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

[Alexandru Ardelean]

On Wed, Jul 21, 2021 at 3:11 AM Théo Borém Fabris <theobf@usp.br> wrote:
>
> Em ter., 20 de jul. de 2021 às 04:22, Alexandru Ardelean
> <ardeleanalex@gmail.com> escreveu:
> >
> > On Mon, Jul 19, 2021 at 6:25 PM Théo Borém Fabris <theobf@usp.br> wrote:
> > >
> > > Hi, Alexandru.
> > >
> > > Em seg., 19 de jul. de 2021 às 04:33, Alexandru Ardelean
> > > <ardeleanalex@gmail.com> escreveu:
> > > >
> > > > On Sun, Jul 18, 2021 at 11:42 PM Théo Borém Fabris <theobf@usp.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@usp.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.
> > > >
> > > Ok.
> > >
> > > > > +}
> > > > > +
> > > > >  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
> > > >
> > > Ok.
> > >
> > > > > +       }
> > > > > +
> > > > >         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.
> > > >
> > > I thought the action added via devm_add_action (and devres_add) was called only
> > > on driver detach, thus the error_disable_reg label would be necessary
> > > to handle the
> >
> > devm_add_action() yes
> > this is devm_add_action_or_reset() which looks like this:
> >
> > static inline int devm_add_action_or_reset(struct device *dev,
> >                        void (*action)(void *), void *data)
> > {
> >     int ret;
> >
> >     ret = devm_add_action(dev, action, data);
> >     if (ret)
> >         action(data);
> >
> >     return ret;
> > }
> >
> > it can be found in "include/linux/device.h"
> >
> > > possible error on regulator_get_voltage. Could you please clarify for
> > > me when does
> > > a driver detach happen?
> >
> > a driver detach happens when:
> > * the kmod is unloaded (assuming the driver is running as a kmod)
> > * manually unbinding the driver from sysfs ;
> >    a quick article about this [it's for USB, but other interfaces use
> >    the same mechanism]:
> >    https://lwn.net/Articles/143397/
> >    there should be something under /sys/bus/spi/drivers/xxxx/unbind
> > * when the system powers down (reboots)
> > * maybe there is some other new method to do this [that I don't know about]
> >
> Thank you so much.
>
> So, should this goto error_disable_reg be replaced by
> "regulator_disable(.); return ret;"?
> ret = regulator_get_voltage(data->vref_reg);
>     if (ret < 0) {
>         dev_err(&client->dev,
>              "Failed to get voltage on regulator: %d\n", ret);
>         goto error_disable_reg;
>     }


This is sufficient:
[ No extra regulator_disable() is required; regulator_disable() gets
called via max5821_regulator_disable() on the error path ]

       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);
               return ret;
       }

>
> > >
> > > Thanks for your reply,
> > > Théo
> > >
> > > > >         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
> > > > >

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

[Théo Borém Fabris]

Thank you, Alexandru and Numo, for your help. I have submitted the
second version.

Théo

Em qua., 21 de jul. de 2021 às 04:23, Alexandru Ardelean
<ardeleanalex@gmail.com> escreveu:
>
> On Wed, Jul 21, 2021 at 3:11 AM Théo Borém Fabris <theobf@usp.br> wrote:
> >
> > Em ter., 20 de jul. de 2021 às 04:22, Alexandru Ardelean
> > <ardeleanalex@gmail.com> escreveu:
> > >
> > > On Mon, Jul 19, 2021 at 6:25 PM Théo Borém Fabris <theobf@usp.br> wrote:
> > > >
> > > > Hi, Alexandru.
> > > >
> > > > Em seg., 19 de jul. de 2021 às 04:33, Alexandru Ardelean
> > > > <ardeleanalex@gmail.com> escreveu:
> > > > >
> > > > > On Sun, Jul 18, 2021 at 11:42 PM Théo Borém Fabris <theobf@usp.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@usp.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.
> > > > >
> > > > Ok.
> > > >
> > > > > > +}
> > > > > > +
> > > > > >  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
> > > > >
> > > > Ok.
> > > >
> > > > > > +       }
> > > > > > +
> > > > > >         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.
> > > > >
> > > > I thought the action added via devm_add_action (and devres_add) was called only
> > > > on driver detach, thus the error_disable_reg label would be necessary
> > > > to handle the
> > >
> > > devm_add_action() yes
> > > this is devm_add_action_or_reset() which looks like this:
> > >
> > > static inline int devm_add_action_or_reset(struct device *dev,
> > >                        void (*action)(void *), void *data)
> > > {
> > >     int ret;
> > >
> > >     ret = devm_add_action(dev, action, data);
> > >     if (ret)
> > >         action(data);
> > >
> > >     return ret;
> > > }
> > >
> > > it can be found in "include/linux/device.h"
> > >
> > > > possible error on regulator_get_voltage. Could you please clarify for
> > > > me when does
> > > > a driver detach happen?
> > >
> > > a driver detach happens when:
> > > * the kmod is unloaded (assuming the driver is running as a kmod)
> > > * manually unbinding the driver from sysfs ;
> > >    a quick article about this [it's for USB, but other interfaces use
> > >    the same mechanism]:
> > >    https://lwn.net/Articles/143397/
> > >    there should be something under /sys/bus/spi/drivers/xxxx/unbind
> > > * when the system powers down (reboots)
> > > * maybe there is some other new method to do this [that I don't know about]
> > >
> > Thank you so much.
> >
> > So, should this goto error_disable_reg be replaced by
> > "regulator_disable(.); return ret;"?
> > ret = regulator_get_voltage(data->vref_reg);
> >     if (ret < 0) {
> >         dev_err(&client->dev,
> >              "Failed to get voltage on regulator: %d\n", ret);
> >         goto error_disable_reg;
> >     }
>
>
> This is sufficient:
> [ No extra regulator_disable() is required; regulator_disable() gets
> called via max5821_regulator_disable() on the error path ]
>
>        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);
>                return ret;
>        }
>
> >
> > > >
> > > > Thanks for your reply,
> > > > Théo
> > > >
> > > > > >         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
> > > > > >