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iio: mma8452: Use correct acceleration units.
author
Martin Fuzzey
<mfuzzey@parkeon.com>
Fri, 7 Nov 2014 13:54:00 +0000
(13:54 +0000)
committer
Jonathan Cameron
<jic23@kernel.org>
Sat, 12 Jul 2014 12:18:55 +0000
(13:18 +0100)
The userspace interface for acceleration sensors is documented as using
m/s^2 units [Documentation/ABI/testing/sysfs-bus-iio]
The fullscale raw value for the mma8452 (-2048) corresponds to -2G, -4G or -8G
depending on the seleted mode.
The scale table was converting to G rather than m/s^2.
Change the scaling table to match the documented interface.
Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Cc: stable@vger.kernel.org
drivers/iio/accel/mma8452.c
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diff --git
a/drivers/iio/accel/mma8452.c
b/drivers/iio/accel/mma8452.c
index 17aeea1705665f799990dd7ae69029c7cf09330c..2a5fa9a436e5cd2c7f495207717e0709774b8d48 100644
(file)
--- a/
drivers/iio/accel/mma8452.c
+++ b/
drivers/iio/accel/mma8452.c
@@
-111,8
+111,14
@@
static const int mma8452_samp_freq[8][2] = {
{6, 250000}, {1, 560000}
};
+/*
+ * Hardware has fullscale of -2G, -4G, -8G corresponding to raw value -2048
+ * The userspace interface uses m/s^2 and we declare micro units
+ * So scale factor is given by:
+ * g * N * 1000000 / 2048 for N = 2, 4, 8 and g=9.80665
+ */
static const int mma8452_scales[3][2] = {
- {0, 9
77}, {0, 1953}, {0, 3906
}
+ {0, 9
577}, {0, 19154}, {0, 38307
}
};
static ssize_t mma8452_show_samp_freq_avail(struct device *dev,