linux-kernel - Re: [PATCH RFC 3/7] hwmon: (da9052) Use devm_regulator_get_enable_get

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Date: Thu, 28 Mar 2024 15:53:28 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Guenter Roeck <linux@...ck-us.net>
Cc: David Lechner <dlechner@...libre.com>, Jonathan Corbet <corbet@....net>,
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, Jean
 Delvare <jdelvare@...e.com>, Support Opensource
 <support.opensource@...semi.com>, Cosmin Tanislav
 <cosmin.tanislav@...log.com>, Lars-Peter Clausen <lars@...afoo.de>, Michael
 Hennerich <Michael.Hennerich@...log.com>, Antoniu Miclaus
 <antoniu.miclaus@...log.com>, Greg Kroah-Hartman
 <gregkh@...uxfoundation.org>, Dmitry Torokhov <dmitry.torokhov@...il.com>,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hwmon@...r.kernel.org, linux-iio@...r.kernel.org,
 linux-staging@...ts.linux.dev, linux-input@...r.kernel.org
Subject: Re: [PATCH RFC 3/7] hwmon: (da9052) Use
 devm_regulator_get_enable_get_voltage()

On Thu, 28 Mar 2024 08:20:00 -0700
Guenter Roeck <linux@...ck-us.net> wrote:

> On 3/28/24 07:20, Jonathan Cameron wrote:
> > On Wed, 27 Mar 2024 18:18:52 -0500
> > David Lechner <dlechner@...libre.com> wrote:
> >   
> >> We can reduce boilerplate code by using
> >> devm_regulator_get_enable_get_voltage().
> >>
> >> Signed-off-by: David Lechner <dlechner@...libre.com>  
> > 
> > A few comments inline, but nothing substantial.
> > 
> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>  
> >> ---
> >>   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.

I was too lazy to look and see if there were existing cases :) Local variable indeed
the right way to go.

> 
> >>   }
> >> @@ -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.


Agreed.  Just a passing comment whilst the code was in front of me.

Jonathan

> 
> Thanks,
> Guenter
>