From: Thomas Betker <thomas.betker@xxxxxxxxxxxxxxxxx>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 97ffae1d30c3f6ceee67d5b0d3e540c08c13c744 ]
The VREFN channel is bipolar, not unipolar. Small negative values do
occur (e.g., -1mV), and unsigned conversion maps them incorrectly to
large positive values (about +1V), so fix this.
Signed-off-by: Thomas Betker <thomas.betker@xxxxxxxxxxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
drivers/iio/adc/xilinx-xadc-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
index 6fa629b..ce93bd8 100644
--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -997,7 +997,7 @@ static const struct iio_event_spec xadc_voltage_events[] = {
.num_event_specs = (_alarm) ? ARRAY_SIZE(xadc_voltage_events) : 0, \
.scan_index = (_scan_index), \
.scan_type = { \
- .sign = 'u', \
+ .sign = ((_addr) == XADC_REG_VREFN) ? 's' : 'u', \
.realbits = 12, \
.storagebits = 16, \
.shift = 4, \
--
2.1.0
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