From 71702e6e52c8312f4c6797a9787d0f8b5656156f Mon Sep 17 00:00:00 2001 From: Martin Fuzzey Date: Fri, 7 Nov 2014 13:54:00 +0000 Subject: [PATCH] iio: mma8452: Use correct acceleration units. 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 Signed-off-by: Jonathan Cameron Cc: stable@vger.kernel.org --- drivers/iio/accel/mma8452.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c index 17aeea170566..2a5fa9a436e5 100644 --- 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, 977}, {0, 1953}, {0, 3906} + {0, 9577}, {0, 19154}, {0, 38307} }; static ssize_t mma8452_show_samp_freq_avail(struct device *dev, -- 2.34.1