Re: [PATCH RFC v3 8/8] iio: ti-adc128s052: Drop variable vref

[Matti Vaittinen]

On 12/04/2025 14:42, Jonathan Cameron wrote:
> On Fri, 11 Apr 2025 08:34:42 -0500
> David Lechner <dlechner@xxxxxxxxxxxx> wrote:
>
> > On 4/7/25 6:37 AM, Matti Vaittinen wrote:
> > > According to Jonathan, variable reference voltages are very rare. It is
> > > unlikely it is needed, and supporting it makes the code a bit more
> > > complex.
> > >
> > > Simplify the driver and drop the variable vref support.
> > >
> > > Suggested-by: Jonathan Cameron <jic23@xxxxxxxxxx>
> > > Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
> > >
> > > ---
> >
> > ...
> >
> > >   static int adc128_probe(struct spi_device *spi)
> > >   {
> > >   	const struct adc128_configuration *config;
> > > @@ -183,17 +173,12 @@ static int adc128_probe(struct spi_device *spi)
> > >   	indio_dev->channels = config->channels;
> > >   	indio_dev->num_channels = config->num_channels;
> > >   
> > > -	adc->reg = devm_regulator_get(&spi->dev, config->refname);
> > > -	if (IS_ERR(adc->reg))
> > > -		return PTR_ERR(adc->reg);
> > > +	adc->vref_mv = devm_regulator_get_enable_read_voltage(&spi->dev,
> > > +							   config->refname);
> > > +	if (adc->vref_mv < 0)
> > > +		return adc->vref_mv;
> > >   
> > > -	ret = regulator_enable(adc->reg);
> > > -	if (ret < 0)
> > > -		return ret;
> > > -	ret = devm_add_action_or_reset(&spi->dev, adc128_disable_regulator,
> > > -				       adc->reg);
> > > -	if (ret)
> > > -		return ret;
> > > +	adc->vref_mv /= 1000;
> >
> > In other drivers, we've been doing:
> >
> > ret = devm_regulator_get_enable_read_voltage(...);
> > if (ret < 0)
> > 	return dev_err_probe(dev, ret, "failed to read '%s' voltage, ...);
> >
> > adc->vref_mv = ret / 1000;
> >
> > It can be easy to make a typo or forget to specify the voltage when creating
> > a .dts, so I think the error message is helpful to catch that.
> >
> > And we use ret to avoid having adc->vref_mv temporarily holding a
> > value with the wrong units (and can make it have an unsigned type).
>
> Good idea.
> Applied patches 1-7. I did tweak this one as well but then couldn't make
> up my mind on whether to change the type of vref_mv so I'll avoid making
> a decision and will leave patch 8 for a v4 from Matti :)

Thanks for handling the 1-7 :) I'll re-spin this, but it's likely to 
take some time. I'm having 2 weeks off from work, and my motorbike and 
boat is requiring some attention ;)

I hope I have regained a lot of energy after 2 weeks ;)

> Jonathan
>
>
>
> > >   
> > >   	if (config->num_other_regulators) {
> > >   		ret = devm_regulator_bulk_get_enable(&spi->dev,


Yours,
	-- Matti