patch "iio: imu: inv_icm42600: Fix temperature calculation" added to char-misc-testing

patch "iio: imu: inv_icm42600: Fix temperature calculation" added to char-misc-testing

[gregkh]

This is a note to let you know that I've just added the patch titled

    iio: imu: inv_icm42600: Fix temperature calculation

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-testing 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 be merged to the char-misc-next branch sometime soon,
after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.


From e2f820014239df9360064079ae93f838ff3b7f8c Mon Sep 17 00:00:00 2001
From: Sean Nyekjaer <sean@geanix.com>
Date: Fri, 2 May 2025 11:37:26 +0200
Subject: iio: imu: inv_icm42600: Fix temperature calculation

>From the documentation:
"offset to be added to <type>[Y]_raw prior toscaling by <type>[Y]_scale"
Offset should be applied before multiplying scale, so divide offset by
scale to make this correct.

Fixes: bc3eb0207fb5 ("iio: imu: inv_icm42600: add temperature sensor support")
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Acked-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
Link: https://patch.msgid.link/20250502-imu-v1-1-129b8391a4e3@geanix.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c
index 213cce1c3111..91f0f381082b 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c
@@ -67,16 +67,18 @@ int inv_icm42600_temp_read_raw(struct iio_dev *indio_dev,
 		return IIO_VAL_INT;
 	/*
 	 * T°C = (temp / 132.48) + 25
-	 * Tm°C = 1000 * ((temp * 100 / 13248) + 25)
+	 * Tm°C = 1000 * ((temp / 132.48) + 25)
+	 * Tm°C = 7.548309 * temp + 25000
+	 * Tm°C = (temp + 3312) * 7.548309
 	 * scale: 100000 / 13248 ~= 7.548309
-	 * offset: 25000
+	 * offset: 3312
 	 */
 	case IIO_CHAN_INFO_SCALE:
 		*val = 7;
 		*val2 = 548309;
 		return IIO_VAL_INT_PLUS_MICRO;
 	case IIO_CHAN_INFO_OFFSET:
-		*val = 25000;
+		*val = 3312;
 		return IIO_VAL_INT;
 	default:
 		return -EINVAL;
-- 
2.49.0