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SubjectRe: [PATCH 2/2] iio: afe: rescale: Implement write_raw
Hi Jonathan,

Le sam. 15 févr. 2020 à 18:32, Jonathan Cameron <jic23@kernel.org> a
écrit :
> On Mon, 10 Feb 2020 19:54:38 -0300
> Paul Cercueil <paul@crapouillou.net> wrote:
>
>> Implement write_raw by converting the value if writing the scale, or
>> just calling the managed channel driver's write_raw otherwise.
>>
>> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
>> ---
>> drivers/iio/afe/iio-rescale.c | 22 ++++++++++++++++++++++
>> 1 file changed, 22 insertions(+)
>>
>> diff --git a/drivers/iio/afe/iio-rescale.c
>> b/drivers/iio/afe/iio-rescale.c
>> index 95802d9ee25e..a48f6af9316d 100644
>> --- a/drivers/iio/afe/iio-rescale.c
>> +++ b/drivers/iio/afe/iio-rescale.c
>> @@ -35,6 +35,27 @@ struct rescale {
>> int *scale_data;
>> };
>>
>> +static int rescale_write_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + int val, int val2, long mask)
>> +{
>> + struct rescale *rescale = iio_priv(indio_dev);
>> + unsigned long long tmp;
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_SCALE:
>> + tmp = val * 1000000000LL;
>> + do_div(tmp, rescale->numerator);
>> + tmp *= rescale->denominator;
>> + do_div(tmp, 1000000000LL);
>> + return iio_write_channel_attribute(rescale->source, tmp, 0,
>> + IIO_CHAN_INFO_SCALE);
>
> Why is val2 always 0? Won't that only work if the backend device
> has integer scales?

Sorry, somehow I didn't see your answer.

Indeed, this will only work if the backend device has integer scales,
but what should I do? Just pass 'val2' instead of 0? Will the value be
correct if I only apply the scale ratio to 'val'?

Cheers,
-Paul


>> + default:
>> + return iio_write_channel_attribute(rescale->source,
>> + val, val2, mask);
>> + }
>> +}
>> +
>> static int rescale_convert(struct rescale *rescale, int type,
>> const int val, const int val2,
>> int *val_out, int *val2_out)
>> @@ -110,6 +131,7 @@ static int rescale_read_avail(struct iio_dev
>> *indio_dev,
>> }
>>
>> static const struct iio_info rescale_info = {
>> + .write_raw = rescale_write_raw,
>> .read_raw = rescale_read_raw,
>> .read_avail = rescale_read_avail,
>> };
>


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