Re: [PATCH V4 2/2] iio: light: isl29018: add optional vdd/vdda regulator operation support

[Phil Reid]

G'day Anson,

Just pulled up the datasheet for this chip.

The absolute max for Vdda is speced as Vddd +/-0.5
With a note that Vdda should be externally shorted to Vddd.


On 11/12/2018 11:43 am, Anson Huang wrote:
> Hi, Phil
>
> Best Regards!
> Anson Huang
>
> > -----Original Message-----
> > From: Phil Reid [mailto:preid@xxxxxxxxxxxxxxxxx]
> > Sent: 2018å12æ11æ 11:36
> > To: Anson Huang <anson.huang@xxxxxxx>; jic23@xxxxxxxxxx;
> > knaack.h@xxxxxx; lars@xxxxxxxxxx; pmeerw@xxxxxxxxxx;
> > robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx; linux-iio@xxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > festevam@xxxxxxxxx
> > Cc: dl-linux-imx <linux-imx@xxxxxxx>
> > Subject: Re: [PATCH V4 2/2] iio: light: isl29018: add optional vdd/vdda
> > regulator operation support
> >
> > On 11/12/2018 11:24 am, Anson Huang wrote:
> > > The light sensor's power supply could be controlled by regulator on
> > > some platforms, such as i.MX6Q-SABRESD board, the light sensor
> > > isl29023's power supply is controlled by a GPIO fixed regulator, need
> > > to make sure the regulator is enabled before any operation of sensor,
> > > this patch adds optional vdd/vdda regulator operation support.
> > >
> > > Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
> > > ---
> > > ChangeLog since V3:
> > > 	- improve the error handling of devm_regulator_get_optional;
> > > 	- make sure regulators are disabled in error path.
> > > ---
> > >    drivers/iio/light/isl29018.c | 83
> > ++++++++++++++++++++++++++++++++++++++++++--
> > >    1 file changed, 80 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/iio/light/isl29018.c
> > > b/drivers/iio/light/isl29018.c index b45400f..a21652b 100644
> > > --- a/drivers/iio/light/isl29018.c
> > > +++ b/drivers/iio/light/isl29018.c
> > > @@ -23,6 +23,7 @@
> > >    #include <linux/mutex.h>
> > >    #include <linux/delay.h>
> > >    #include <linux/regmap.h>
> > > +#include <linux/regulator/consumer.h>
> > >    #include <linux/slab.h>
> > >    #include <linux/iio/iio.h>
> > >    #include <linux/iio/sysfs.h>
> > > @@ -95,6 +96,8 @@ struct isl29018_chip {
> > >    	struct isl29018_scale	scale;
> > >    	int			prox_scheme;
> > >    	bool			suspended;
> > > +	struct regulator	*vdd_reg;
> > > +	struct regulator	*vdda_reg;
> > >    };
> > >
> > >    static int isl29018_set_integration_time(struct isl29018_chip *chip,
> > > @@ -735,6 +738,34 @@ static int isl29018_probe(struct i2c_client
> > > *client,
> > >
> > >    	mutex_init(&chip->lock);
> > >
> > > +	chip->vdd_reg = devm_regulator_get_optional(&client->dev, "vdd");
> > > +	if (!IS_ERR(chip->vdd_reg)) {
> > > +		err = regulator_enable(chip->vdd_reg);
> > > +		if (err) {
> > > +			dev_err(&client->dev, "failed to enable VDD regulator\n");
> > > +			return err;
> > > +		}
> > > +	} else {
> > > +		err = PTR_ERR(chip->vdd_reg);
> > > +		if (err != -ENODEV)
> > > +			return err;
> > > +	}
> > > +
> > > +	chip->vdda_reg = devm_regulator_get_optional(&client->dev, "vdda");
> > > +	if (!IS_ERR(chip->vdda_reg)) {
> > > +		err = regulator_enable(chip->vdda_reg);
> > > +		if (err) {
> > > +			dev_err(&client->dev, "failed to enable VDDA regulator\n");
> > > +			if (!IS_ERR(chip->vdd_reg))
> > > +				regulator_disable(chip->vdd_reg);
> > > +			return err;
Not sure about this case at the call to enable failed so I think
you only want the first one to be disabled.
You could add another goto statement thou, see below.


> > > +		}
> > > +	} else {
> > > +		err = PTR_ERR(chip->vdda_reg);
> > > +		if (err != -ENODEV)
> > > +			return err;
> > maybe goto disable_regulators; to disable vdd.
>
> Agree, I will use " goto disable_regulators;" in both here and upper regulator enable fail case.
> Please help review V5, thanks.

Here its safe to call both as vdda_reg will be an error ptr.

> Anson
>
> > > +	}
> > > +
> > >    	chip->type = dev_id;
> > >    	chip->calibscale = 1;
> > >    	chip->ucalibscale = 0;
> > > @@ -747,12 +778,12 @@ static int isl29018_probe(struct i2c_client *client,
> > >    	if (IS_ERR(chip->regmap)) {
> > >    		err = PTR_ERR(chip->regmap);
> > >    		dev_err(&client->dev, "regmap initialization fails: %d\n", err);
> > > -		return err;
> > > +		goto disable_regulators;
> > >    	}
> > >
> > >    	err = isl29018_chip_init(chip);
> > >    	if (err)
> > > -		return err;
> > > +		goto disable_regulators;
> > >
> > >    	indio_dev->info = isl29018_chip_info_tbl[dev_id].indio_info;
> > >    	indio_dev->channels = isl29018_chip_info_tbl[dev_id].channels;
> > > @@ -761,13 +792,24 @@ static int isl29018_probe(struct i2c_client *client,
> > >    	indio_dev->dev.parent = &client->dev;
> > >    	indio_dev->modes = INDIO_DIRECT_MODE;
> > >
> > > -	return devm_iio_device_register(&client->dev, indio_dev);
> > > +	err = devm_iio_device_register(&client->dev, indio_dev);
> > > +	if (!err)
> > > +		return 0;
> > > +
> > > +disable_regulators:
> > > +	if (!IS_ERR(chip->vdd_reg))
> > > +		regulator_disable(chip->vdd_reg);
> > > +	if (!IS_ERR(chip->vdda_reg))
> > > +		regulator_disable(chip->vdda_reg);
> > > +
eg: extra label here.
Order is changed thou, which may be a problem.
It's in the reverse order to the enable, which is usually what you want but the
datasheet concerns above may be an issue.


disable_regulators:
	if (!IS_ERR(chip->vdda_reg))
		regulator_disable(chip->vdda_reg);
disable_regulator_vdd:
	if (!IS_ERR(chip->vdd_reg))
		regulator_disable(chip->vdd_reg);

> > > +	return err;
> > >    }
> > [snip]



--
Regards
Phil