This is a note to let you know that I've just added the patch titled
iio: mxs-lradc: Fix temperature offset
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iio-mxs-lradc-fix-temperature-offset.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b94e22805a2224061bb263a82b72e09544a5fbb3 Mon Sep 17 00:00:00 2001
From: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
Date: Wed, 7 Oct 2015 13:10:54 +0200
Subject: iio: mxs-lradc: Fix temperature offset
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From: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
commit b94e22805a2224061bb263a82b72e09544a5fbb3 upstream.
0° Kelvin is actually −273.15°C, not -272.15°C. Fix the temperature offset.
Also improve the comment explaining the calculation.
Reported-by: Janusz Użycki <j.uzycki@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
Acked-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Acked-by: Marek Vasut <marex@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/iio/adc/mxs-lradc.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -920,11 +920,12 @@ static int mxs_lradc_read_raw(struct iio
case IIO_CHAN_INFO_OFFSET:
if (chan->type == IIO_TEMP) {
/* The calculated value from the ADC is in Kelvin, we
- * want Celsius for hwmon so the offset is
- * -272.15 * scale
+ * want Celsius for hwmon so the offset is -273.15
+ * The offset is applied before scaling so it is
+ * actually -213.15 * 4 / 1.012 = -1079.644268
*/
- *val = -1075;
- *val2 = 691699;
+ *val = -1079;
+ *val2 = 644268;
return IIO_VAL_INT_PLUS_MICRO;
}
Patches currently in stable-queue which might be from alexandre.belloni@xxxxxxxxxxxxxxxxxx are
queue-3.14/iio-mxs-lradc-fix-temperature-offset.patch
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