diff options
| author | Cong Nguyen <congnt264@gmail.com> | 2026-08-10 23:44:46 +0700 |
|---|---|---|
| committer | Jonathan Cameron <jonathan.cameron@oss.qualcomm.com> | 2026-08-31 00:52:40 +0100 |
| commit | 91908c0a78baddc8572aa3ab69e62ee2eb496ba4 (patch) | |
| tree | 2d79fac4dfc97dbb05bf8ed9cbee8d67d2547860 /drivers/iio | |
| parent | fafefa925ed7ec10383d9bf0378abf878b7f13cb (diff) | |
iio: adc: max1363: sign-extend bipolar differential channel reads
MAX1363 differential channels are bipolar, but max1363_read_single_chan()
masks the raw value to the ADC resolution without sign-extending it.
Negative differential readings are therefore reported to userspace as
large positive values (e.g. -1 as 4095 on a 12-bit part).
Sign-extend the masked value from the resolution bit for differential
channels. Single-ended channels are unipolar and are left unchanged.
Fixes: d1325cf45077 ("Staging: IIO: max1363 ADC driver")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4
Signed-off-by: Cong Nguyen <congnt264@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
Diffstat (limited to 'drivers/iio')
| -rw-r--r-- | drivers/iio/adc/max1363.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/iio/adc/max1363.c b/drivers/iio/adc/max1363.c index 65a2d92bb112..629c53af6472 100644 --- a/drivers/iio/adc/max1363.c +++ b/drivers/iio/adc/max1363.c @@ -404,6 +404,14 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev, data = rxbuf[0]; } + + /* + * Differential channels are bipolar and the device returns the sample + * in two's complement, so sign-extend it from the resolution bit. + */ + if (chan->differential) + data = sign_extend32(data, st->chip_info->bits - 1); + *val = data; return 0; |