Re: [PATCH v2 5/5] iio: mxs-lradc: add write_raw function to modifyscale

[Hector Palacios]

Dear Marek,

On 07/19/2013 06:17 PM, Marek Vasut wrote:
> > Here you have three entries per channel:
> > in_voltageX_raw		-> the sample raw value
> > in_voltageX_scale	-> the scale to multiply the raw value to get the
> voltage
> > in mV in_voltageX_scale_available -> lists the available scales of the
> > channel
> >
> > For example for channel 0:
> >
> > # cat in_voltage0_scale_available
> > 0.451660156 0.903320312	(two scales available, first with divider by two
> > disabled, second with divider by two enabled)
> >
> > # cat in_voltage0_scale
> > 0.451660156			(divider by two is currently disabled)
> >
> > # cat in_voltage0_raw		(shows measured value)
> > 1000
> >
> > If you multiply the value by the scale you get: 1000 * 0.451660156 = 451.6
> > mV
> >
> > # echo 0.903320312 > in_voltage0_scale	(enables the divider by two)
>
> Ok, so I have to remember this value : '0.903320312' in case I want to enable
> divide-by-two functionality?

No you don't. That's why there is a 'in_voltage_scale_available' that lists the 
available values.

> Hmmmm ... why would this interface not work:
> echo 2 > in_voltage0_scale
>
> or
>
> echo 1 > in_voltage0_scale

An easy thing like that is what I first submitted, but it was rejected and I was told 
to use the scale_available descriptor instead, which is the common interface the rest 
of drivers use.

Best regards,
--
Hector Palacios
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