From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mta1.parkeon.com ([91.121.43.66]:43138 "EHLO mta1.parkeon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753670AbaGKN1k (ORCPT ); Fri, 11 Jul 2014 09:27:40 -0400 Subject: [PATCH] iio: mma8452: Use correct acceleration units. To: linux-iio@vger.kernel.org, Jonathan Cameron From: Martin Fuzzey Date: Fri, 11 Jul 2014 14:54:31 +0200 Message-ID: <20140711125431.22109.59659.stgit@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org 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 --- 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} }; +/* 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,