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

Jonathan Cameron
2024-03-28T15:53:44Z

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

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