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

Matti Vaittinen
2025-04-14T06:03:11Z

On 12/04/2025 14:42, Jonathan Cameron wrote:
> On Fri, 11 Apr 2025 08:34:42 -0500
> David Lechner <dlechner@baylibre.com> 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@kernel.org>
>>> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
>>>
>>> ---
>>
>> ...
>>
>>> 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