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Subject: Re: [PATCH v2 1/2] iio: adc: ti-ads7950: Allow to use on ACPI
 platforms
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>,
        Lars-Peter Clausen <lars@metafoo.de>, linux-iio@vger.kernel.org
References: <20170728222015.43574-1-andriy.shevchenko@linux.intel.com>
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 <1501602326.29303.332.camel@linux.intel.com>
From: David Lechner <david@lechnology.com>
Message-ID: <51d5783f-4a7d-b51e-fd45-e4d84576f1c3@lechnology.com>
Date: Tue, 1 Aug 2017 11:21:50 -0500
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On 08/01/2017 10:45 AM, Andy Shevchenko wrote:
>    
>>>> +	/* Use hard coded value for reference voltage in ACPI
>>>> case */
>>>> +	if (ACPI_COMPANION(&spi->dev))
>>>> +		st->vref_mv = TI_ADS7950_VA_MV_ACPI_DEFAULT;
>>>
>>> Instead of checking or ACPI, you could just say "if we have a dummy
>>> regulator, then use the default value".
> 
> 
>> Agreed. Sounds sensible to me.  Hopefully in DT people will
>> provide the right regulator, but chances are this won't
>> always happen.
> 
> There is no call like
> regulator_is_dummy()
> (and, looking into the code of regulator framework, can't be)
> 
> Can you elaborate a bit, maybe I'm missing something obvious?
> 

I haven't tested this, but shouldn't regulator_get_voltage() return an 
error for a dummy regulator? You could use this as your test.

static int ti_ads7950_get_range(struct ti_ads7950_state *st)
{
	int vref;

	vref = regulator_get_voltage(st->reg);
	if (vref < 0)
-		return vref;
+		vref = 2500000;

	vref /= 1000;

	if (st->settings & TI_ADS7950_CR_RANGE_5V)
		vref *= 2;

	return vref;
}