On Fri Jul 23, 2021 at 5:16 PM EDT, Peter Rosin wrote:

On 2021-07-21 05:06, Liam Beguin wrote:

quoted

From: Liam Beguin <redacted>

Some ADCs use IIO_VAL_INT_PLUS_{NANO,MICRO} scale types.
Add support for these to allow using the iio-rescaler with them.

Signed-off-by: Liam Beguin <redacted>
---
 drivers/iio/afe/iio-rescale.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index d0669fd8eac5..2b73047365cc 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c

@@ -41,6 +41,20 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
 		do_div(tmp, 1000000000LL);
 		*val = tmp;
 		return scale_type;
+	case IIO_VAL_INT_PLUS_NANO:
+		tmp = ((s64)*val * 1000000000LL + *val2) * rescale->numerator;
+		tmp = div_s64(tmp, rescale->denominator);
+
+		*val = div_s64(tmp, 1000000000LL);
+		*val2 = tmp - *val * 1000000000LL;
+		return scale_type;

Hi Peter,

Hi!

My objection from v5 still stands. Did you forget or did you simply send
the
wrong patch?

Apologies, again I didn't mean to make it seem like I ignored your comments.
I tried your suggestion, but had issues when *val2 would overflow into
the integer part.
Even though what I has was more prone to integer overflow with the first
multiplication, I thought it was still a valid solution as it passed the
tests.

Untested suggestion, this time handling negative values and
canonicalizing any
overflow from the fraction calculation.

neg = *val < 0 || *val2 < 0;
tmp = (s64)abs(*val) * rescale->numerator;
rem = do_div(tmp, rescale->denominator);
*val = tmp;
tmp = rem * 1000000000LL + (s64)abs(*val2) * rescale->numerator;
do_div(tmp, rescale->denominator);
*val2 = do_div(tmp, 1000000000LL);
*val += tmp;
if (neg) {
if (*val < 0)
*val = -*val;
else
*val2 = -*val;

I'll look into this suggestion.

}

quoted

+	case IIO_VAL_INT_PLUS_MICRO:
+		tmp = ((s64)*val * 1000000LL + *val2) * rescale->numerator;
+		tmp = div_s64(tmp, rescale->denominator);
+
+		*val = div_s64(tmp, 1000000);

Why do you not have the LL suffix here?

Doesnt' LL make it into a 64 bit integer?
I left it out because the second parameter of div_s64() should be s32.

Thanks,
Liam

Cheers,
Peter

quoted

+		*val2 = tmp - *val * 1000000;
+		return scale_type;
 	default:
 		return -EOPNOTSUPP;
 	}