linux-kernel - [PATCH 5.13 097/800] iio: accel: bmc150: Fix bma222 scale unit

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Date:   Mon, 12 Jul 2021 08:02:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org>,
        Stephan Gerhold <stephan@...hold.net>, Stable@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: [PATCH 5.13 097/800] iio: accel: bmc150: Fix bma222 scale unit

From: Stephan Gerhold <stephan@...hold.net>

commit 6e2a90af0b8d757e850cc023d761ee9a9492e2fe upstream.

According to sysfs-bus-iio documentation the unit for accelerometer
values after applying scale/offset should be m/s^2, not g, which explains
why the scale values for the other variants in bmc150-accel do not match
exactly the values given in the datasheet.

To get the correct values, we need to multiply the BMA222 scale values
by g = 9.80665 m/s^2.

Fixes: a1a210bf29a1 ("iio: accel: bmc150-accel: Add support for BMA222")
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Stephan Gerhold <stephan@...hold.net>
Link: https://lore.kernel.org/r/20210611080903.14384-2-stephan@gerhold.net
Cc: <Stable@...r.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/iio/accel/bmc150-accel-core.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/drivers/iio/accel/bmc150-accel-core.c
+++ b/drivers/iio/accel/bmc150-accel-core.c
@@ -1177,11 +1177,12 @@ static const struct bmc150_accel_chip_in
 		/*
 		 * The datasheet page 17 says:
 		 * 15.6, 31.3, 62.5 and 125 mg per LSB.
+		 * IIO unit is m/s^2 so multiply by g = 9.80665 m/s^2.
 		 */
-		.scale_table = { {156000, BMC150_ACCEL_DEF_RANGE_2G},
-				 {313000, BMC150_ACCEL_DEF_RANGE_4G},
-				 {625000, BMC150_ACCEL_DEF_RANGE_8G},
-				 {1250000, BMC150_ACCEL_DEF_RANGE_16G} },
+		.scale_table = { {152984, BMC150_ACCEL_DEF_RANGE_2G},
+				 {306948, BMC150_ACCEL_DEF_RANGE_4G},
+				 {612916, BMC150_ACCEL_DEF_RANGE_8G},
+				 {1225831, BMC150_ACCEL_DEF_RANGE_16G} },
 	},
 	[bma222e] = {
 		.name = "BMA222E",