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Patch "iio: mxs-lradc: Fix temperature offset" has been added to the 3.14-stable tree

PATCH [email protected] 1 participant 1 message Nov 6, 2015

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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 <[email protected]> know about it.

Quoted 1 line

From b94e22805a2224061bb263a82b72e09544a5fbb3 Mon Sep 17 00:00:00 2001

From: Alexandre Belloni <[email protected]>
Date: Wed, 7 Oct 2015 13:10:54 +0200
Subject: iio: mxs-lradc: Fix temperature offset
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Alexandre Belloni <[email protected]>

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.

---
 drivers/staging/iio/adc/mxs-lradc.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
drivers/staging/iio/adc/mxs-lradc.c +5 -4
@@ -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 [email protected] are

queue-3.14/iio-mxs-lradc-fix-temperature-offset.patch