On 12/07/14 11:50, Hartmut Knaack wrote:
Martin Fuzzey schrieb:
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@xxxxxxxxxxx>
Fixed up and applied to the fixes-togreg branch of iio.git.
Also marked for stable.
Thanks,
J
---
drivers/iio/accel/mma8452.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index 17aeea1..61eba5a 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -111,8 +111,13 @@ static const int mma8452_samp_freq[8][2] = {
{6, 250000}, {1, 560000}
};
The first line of the comment should just contain /*
+/* 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,
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