This is a note to let you know that I've just added the patch titled
iio: mxs-lradc: Fix temperature offset
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>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
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 <[email protected]>
Signed-off-by: Alexandre Belloni <[email protected]>
Acked-by: Stefan Wahren <[email protected]>
Acked-by: Marek Vasut <[email protected]>
Cc: <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>
---
drivers/staging/iio/adc/mxs-lradc.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/iio/adc/mxs-lradc.c
b/drivers/staging/iio/adc/mxs-lradc.c
index 3f7715c9968b..47fc00a3f63b 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -915,11 +915,12 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
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;
}
--
2.6.1
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