On Tue, May 26, 2015 at 03:41:42PM -0500, Chris Lesiak wrote:
> The function ntc_adc_iio_read was using iio_read_channel_raw and
> converting to microVolts using the assumption of a 12 bit ADC. If a
> converter with different precision was used, the result was in error.
>
> Instead, use iio_read_channel_processed, which does the conversion to
> microVolts itself.
>
> Signed-off-by: Chris Lesiak <chris.lesiak@xxxxxxxxx>
> ---
> drivers/hwmon/ntc_thermistor.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
> index 6880011..0d3a686 100644
> --- a/drivers/hwmon/ntc_thermistor.c
> +++ b/drivers/hwmon/ntc_thermistor.c
> @@ -190,20 +190,15 @@ struct ntc_data {
> static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
> {
> struct iio_channel *channel = pdata->chan;
> - s64 result;
> int val, ret;
>
> - ret = iio_read_channel_raw(channel, &val);
> + ret = iio_read_channel_processed(channel, &val);
> if (ret < 0) {
> pr_err("read channel() error: %d\n", ret);
> return ret;
> }
>
> - /* unit: mV */
> - result = pdata->pullup_uv * (s64) val;
> - result >>= 12;
> -
> - return (int)result;
> + return val;
The calculation used to need pullup_uv. As far as I can see,
the iio driver knows nothing about pullup_uv, which makes me
wonder how this can work. Can you explain ?
Thanks,
Guenter
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