Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102

From	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102
Date	2017-05-05 22:40 +0200
Message-ID	<tDSb7-6HT-3@gated-at.bofh.it> (permalink)
References	<tDF4d-6re-3@gated-at.bofh.it> <tDIbM-8pT-5@gated-at.bofh.it> <tDIOu-vu-17@gated-at.bofh.it> <tDQCm-5yw-33@gated-at.bofh.it> <tDRRM-6Av-23@gated-at.bofh.it>
Organization	Intel Finland Oy

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On Fri, 2017-05-05 at 22:09 +0200, Jan Kiszka wrote:
> On 2017-05-05 20:52, Jonathan Cameron wrote:
> > On 05/05/17 11:39, Jan Kiszka wrote:
> > > On 2017-05-05 11:54, Andy Shevchenko wrote:
> > > > On Fri, 2017-05-05 at 08:31 +0200, Jan Kiszka wrote:

>>>>> +			if (st->reg)
> > > > > +				*val =
> > > > > regulator_get_voltage(st->reg) 
> > > > > / 1000;
> > > > > +			else
> > > > > +				*val = st->va_millivolt;
> > > > > +
> > > > 
> > > > Another way is to not just hard code the value, but create a
> > > > fixed
> > > > voltage regulator out of it. In this case you will have one way
> > > > to get
> > > > its value.
> > > 
> > > That's a good idea.
> > 
> > Agreed. Make sure to cc Mark Brown though as I'll need an ack from
> > him
> > to have a fixed reg hiding in here.
> 
> After diving deeper, it not longer appears to be a good idea:
> 
> - pulls in a non-obvious requirement for CONFIG_REGULATOR on platforms
>   that otherwise do not need it

Why is it a problem?

> - requires complex life-cycle management so that the fixed regulator
> is
>   instantiated on the first device creation and removed with the last
>   one

Who cares if you register more than one?

> We better go with the static value assignment.
> 
> I'll move that regulator_get_voltage into the probing function which
> will simplify things further (va_millivolt will carry the value for
> both
> cases).

Yes, it would be the way, if system has it's fixed.

But in this case you need to threat regulator as optional if we are
going to enable/disable them for PM.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Thread

[PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-05 08:40 +0200
  Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Mika Westerberg <mika.westerberg@linux.intel.com> - 2017-05-05 11:50 +0200
    Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-05 12:30 +0200
      Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Mika Westerberg <mika.westerberg@linux.intel.com> - 2017-05-05 12:50 +0200
        Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jonathan Cameron <jic23@kernel.org> - 2017-05-05 21:00 +0200
  Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and  ADC128S102 Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2017-05-05 12:00 +0200
    Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-05 12:40 +0200
      Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jonathan Cameron <jic23@kernel.org> - 2017-05-05 21:00 +0200
        Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jan Kiszka <jan.kiszka@siemens.com> - 2017-05-05 22:20 +0200
          Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and  ADC128S102 Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2017-05-05 22:40 +0200
            Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jonathan Cameron <jic23@kernel.org> - 2017-05-08 00:00 +0200
  Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jonathan Cameron <jic23@kernel.org> - 2017-05-05 21:00 +0200
    Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and  ADC128S102 Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2017-05-05 21:10 +0200
      Re: [PATCH v3] iio: adc: Add support for TI ADC108S102 and ADC128S102 Jonathan Cameron <jic23@kernel.org> - 2017-05-08 00:00 +0200

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