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From: Stephan Gerhold <stephan@gerhold.net>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>,
	Rob Herring <robh+dt@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Peter Meerwald <pmeerw@pmeerw.net>,
	linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
	Bastien Nocera <hadess@hadess.net>,
	Hans de Goede <hdegoede@redhat.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	~postmarketos/upstreaming@lists.sr.ht,
	Stephan Gerhold <stephan@gerhold.net>
Subject: [PATCH v3 01/10] iio: accel: bmc150: Fix bma222 scale unit
Date: Fri, 11 Jun 2021 10:08:54 +0200	[thread overview]
Message-ID: <20210611080903.14384-2-stephan@gerhold.net> (raw)
In-Reply-To: <20210611080903.14384-1-stephan@gerhold.net>

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@linaro.org>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
---
Added this patch in v2 to avoid conflicts later in case this
should be backported to a stable kernel.
---
 drivers/iio/accel/bmc150-accel-core.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c
index a3d08d713362..a80ee0fdabc5 100644
--- a/drivers/iio/accel/bmc150-accel-core.c
+++ b/drivers/iio/accel/bmc150-accel-core.c
@@ -1145,11 +1145,12 @@ static const struct bmc150_accel_chip_info bmc150_accel_chip_info_tbl[] = {
 		/*
 		 * 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",
-- 
2.32.0


  reply	other threads:[~2021-06-11  8:11 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-11  8:08 [PATCH v3 00/10] iio: accel: bmc150: Add support for BMA253/BMA254 Stephan Gerhold
2021-06-11  8:08 ` Stephan Gerhold [this message]
2021-06-11  8:08 ` [PATCH v3 02/10] iio: accel: bmc150: Clarify combo modules in Kconfig Stephan Gerhold
2021-06-11  8:08 ` [PATCH v3 03/10] iio: accel: bmc150: Drop misleading/duplicate chip identifiers Stephan Gerhold
2021-06-11  8:08 ` [PATCH v3 04/10] iio: accel: bmc150: Drop duplicated documentation of supported chips Stephan Gerhold
2021-06-11  8:08 ` [PATCH v3 05/10] iio: accel: bmc150: Sort all chip names alphabetically / by chip ID Stephan Gerhold
2021-06-11  8:08 ` [PATCH v3 06/10] dt-bindings: iio: accel: bma255: Document bosch,bma253 Stephan Gerhold
2021-06-11  8:09 ` [PATCH v3 07/10] iio: accel: bmc150: Add device IDs for BMA253 Stephan Gerhold
2021-06-11  8:09 ` [PATCH v3 08/10] dt-bindings: iio: bma255: Allow multiple interrupts Stephan Gerhold
2021-06-11 17:59   ` Jonathan Cameron
2021-06-11 18:21     ` Stephan Gerhold
2021-06-11 18:26       ` Jonathan Cameron
2021-06-11 19:21         ` Stephan Gerhold
2021-06-11  8:09 ` [PATCH v3 09/10] dt-bindings: iio: accel: bma180/bma255: Move bma254 to bma255 schema Stephan Gerhold
2021-06-11  8:09 ` [PATCH v3 10/10] iio: accel: bma180/bmc150: Move BMA254 to bmc150-accel driver Stephan Gerhold
2021-06-11 17:35 ` [PATCH v3 00/10] iio: accel: bmc150: Add support for BMA253/BMA254 Jonathan Cameron

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