[PATCH] staging: iio: ad5933: fix handling of settling time cycles

From: Luis de Bethencourt
Date: Wed Jun 01 2016 - 11:55:37 EST


Correctly handle the settling time cycles value. The else branch was an
impossible condition (> 1022 in the else branch of > 511) and the handling
of the values was dividing by 2 and 4, with a left shift, instead of
multiplying.

Based on the Table 13 at the bottom of Page 25 of the Data Sheet:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD5933.pdf

Signed-off-by: Luis de Bethencourt <luisbg@xxxxxxxxxxxxxxx>
---

Hi,

I decided to use the hexadecimal values instead of (1 << 10) and (1 << 9), for
briefness, I could resend using those instead if it is prefered.

I also decided to use multiplications instead of right-shifts for readability.
I could use change that as well.

Thanks,
Luis

drivers/staging/iio/impedance-analyzer/ad5933.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
index 9f43976..3a2cf8f3 100644
--- a/drivers/staging/iio/impedance-analyzer/ad5933.c
+++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
@@ -444,10 +444,13 @@ static ssize_t ad5933_store(struct device *dev,
st->settling_cycles = val;

/* 2x, 4x handling, see datasheet */
- if (val > 511)
- val = (val >> 1) | (1 << 9);
- else if (val > 1022)
- val = (val >> 2) | (3 << 9);
+ if (val & 0x400 && val & 0x200) {
+ val &= 0x1ff;
+ val *= 4;
+ } else if (val & 0x200) {
+ val &= 0x1ff;
+ val *= 2;
+ }

dat = cpu_to_be16(val);
ret = ad5933_i2c_write(st->client,
--
2.5.1