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

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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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