linux-kernel - RE: [PATCH v2] iio: adc: add new lp8788 adc driver

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Message-ID: <f1f77ced-be0d-4501-b38d-91a796170649@email.android.com>
Date:	Thu, 16 Aug 2012 06:36:16 +0100
From:	Jonathan Cameron <jic23@...23.retrosnub.co.uk>
To:	"Kim, Milo" <Milo.Kim@...com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	"jic23@....ac.uk" <jic23@....ac.uk>
CC:	"jic23@...nel.org" <jic23@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	"sameo@...ux.intel.com" <sameo@...ux.intel.com>
Subject: RE: [PATCH v2] iio: adc: add new lp8788 adc driver



"Kim, Milo" <Milo.Kim@...com> wrote:

>> > +	switch (mask) {
>> > +	case IIO_CHAN_INFO_RAW:
>> > +		*val = result;
>> > +		return IIO_VAL_INT;
>> > +	case IIO_CHAN_INFO_SCALE:
>> > +		*val = adc_const[id] * ((result * 1000 + 500) / 1000);
>> 
>> This looks wrong. The IIO_CHAN_INFO_SCALE attribute is the factor by
>> which
>> IIO_CHAN_INFO_RAW needs to be multiplied to get the value in the
>proper
>> unit,
>> which is specified in the IIO ABI spec. E.g. milli volts for
>voltages.
>> 
>> What you return here seems to be the IIO_CHAN_INFO_PROCESSED
>attribute.
>> Which
>> basically is raw * scale.
>
>Thanks a lot for your review.
>
>Any way to get the result with offset value in the iio-consumer side?
>What I need is as below.
>
>  result = raw * scale + offset
>
>At this moment, there are two apis() for reading the iio channel
>- iio_read_channel_raw() and iio_read_channel_scale().
>
>Does it sound good if I add iio_read_channel_offset() consumer api
>using IIO_CHAN_INFO_OFFSET?

Yes. Please add that.
>
>Best Regards,
>Milo

-- 
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