On 2015-09-22 20:22, Jonathan Cameron wrote:
> On 22 September 2015 16:36:49 BST, Peter Rosin <peda@xxxxxxxxxxxxxx> wrote:
*snip* lots of cosmetics that I'll fix in the next spin...
>> +
>> +static int mcp4531_read_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + int *val, int *val2, long mask)
>> +{
>> + int err;
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_RAW:
>> + err = mcp4531_get_value(indio_dev, chan->address, val);
>> + if (err < 0)
>> + return err;
>> + return IIO_VAL_INT;
>> + }
> No scale known? Be nice to relate to real world values. I gather this may need
> platform data of some type (can't open data sheet on phone for some reason)
...but I need more input on this.
Yes, it would be nice and yes it requires platform data, as there is
no way to retrieve if the driver is dealing with a 5, 10, 50 or 100 kOhms
pot/rheostat. You would also have to expose both the resistance between
A to W and between W to B, as you have no way to know how it's been
connected (or you'd need more platform data). Ok, for rheostats you
know how it's connected, since A isn't available, but for pots there
are two resistance values controlled with a single value X i.e.
X*scale/max and (max-X)*scale/max (ignoring the 75 Ohm wiper resistance).
But, I'd rather not go there, as I don't need any of it. Is it Ok to not
provide scaling?
Cheers,
Peter
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