From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net ([212.227.17.20]:56241 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752025AbaGLKvH (ORCPT ); Sat, 12 Jul 2014 06:51:07 -0400 Message-ID: <53C11313.20803@gmx.de> Date: Sat, 12 Jul 2014 12:50:59 +0200 From: Hartmut Knaack MIME-Version: 1.0 To: Martin Fuzzey , linux-iio@vger.kernel.org, Jonathan Cameron Subject: Re: [PATCH] iio: mma8452: Use correct acceleration units. References: <20140711125431.22109.59659.stgit@localhost> In-Reply-To: <20140711125431.22109.59659.stgit@localhost> Content-Type: text/plain; charset=UTF-8 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org 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 > --- > 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, > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >