Re: [PATCH RFC 3/7] hwmon: (da9052) Use devm_regulator_get_enable_get_voltage()

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On 3/28/24 07:20, Jonathan Cameron wrote:
> On Wed, 27 Mar 2024 18:18:52 -0500
> David Lechner <dlechner@xxxxxxxxxxxx> wrote:
>
> > We can reduce boilerplate code by using
> > devm_regulator_get_enable_get_voltage().
> >
> > Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
>
> A few comments inline, but nothing substantial.
>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> > ---
> >   drivers/hwmon/da9052-hwmon.c | 33 +++++++--------------------------
> >   1 file changed, 7 insertions(+), 26 deletions(-)
> >
> > diff --git a/drivers/hwmon/da9052-hwmon.c b/drivers/hwmon/da9052-hwmon.c
> > index 2bd7ae8100d7..70e7bc72e980 100644
> > --- a/drivers/hwmon/da9052-hwmon.c
> > +++ b/drivers/hwmon/da9052-hwmon.c
> > @@ -26,7 +26,6 @@ struct da9052_hwmon {
> >   	struct mutex		hwmon_lock;
> >   	bool			tsi_as_adc;
> >   	int			tsiref_mv;
> > -	struct regulator	*tsiref;
> >   	struct completion	tsidone;
> >   };
> >   
> > @@ -414,32 +413,19 @@ static int da9052_hwmon_probe(struct platform_device *pdev)
> >   		device_property_read_bool(pdev->dev.parent, "dlg,tsi-as-adc");
> >   
> >   	if (hwmon->tsi_as_adc) {
> > -		hwmon->tsiref = devm_regulator_get(pdev->dev.parent, "tsiref");
> > -		if (IS_ERR(hwmon->tsiref)) {
> > -			err = PTR_ERR(hwmon->tsiref);
> > -			dev_err(&pdev->dev, "failed to get tsiref: %d", err);
> > +		err = devm_regulator_get_enable_get_voltage(pdev->dev.parent,
> > +							    "tsiref");
> > +		if (err < 0)
> >   			return err;
> > -		}
> > -
> > -		err = regulator_enable(hwmon->tsiref);
> > -		if (err)
> > -			return err;
> > -
> > -		hwmon->tsiref_mv = regulator_get_voltage(hwmon->tsiref);
> > -		if (hwmon->tsiref_mv < 0) {
> > -			err = hwmon->tsiref_mv;
> > -			goto exit_regulator;
> > -		}
> >   
> >   		/* convert from microvolt (DT) to millivolt (hwmon) */
> > -		hwmon->tsiref_mv /= 1000;
> > +		hwmon->tsiref_mv = err / 1000;
>
> Using a variable called err for a good value is a bit ugly but fair enough if that
> is precedence in this driver.

It isn't. The existing code assigns the return value from regulator_get_voltage()
to hwmon->tsiref_mv and then evaluates it. I would not oppose introducing a variable
such as tsiref_uv, but not the misuse of 'err'. I am not going to accept the code
as suggested. It is bad style, and it would invite others to use it as precedent
when trying to introduce similar code.

> >   }
> > @@ -483,10 +466,8 @@ static void da9052_hwmon_remove(struct platform_device *pdev)
> >   {
> >   	struct da9052_hwmon *hwmon = platform_get_drvdata(pdev);
> >   
> > -	if (hwmon->tsi_as_adc) {
> > +	if (hwmon->tsi_as_adc)
> >   		da9052_free_irq(hwmon->da9052, DA9052_IRQ_TSIREADY, hwmon);
> Superficially looks like devm_da9052_request_irq could be added that
> uses devm_request_threaded_irq() to allow dropping this remaining handling.

That should be a separate series of patches. A local solution might be
to use devm_add_action_or_reset(), but that should also be a separate patch.

Thanks,
Guenter