From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Cameron Subject: Re: [PATCH v3 8/9] staging: iio: ad2s1200: Add scaling factor for angle channel Date: Sat, 28 Apr 2018 18:37:22 +0100 Message-ID: <20180428183722.489e2a71@archlinux> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" To: David Veenstra Cc: devel@driverdev.osuosl.org, devicetree@vger.kernel.org, lars@metafoo.de, Michael.Hennerich@analog.com, linux-iio@vger.kernel.org, robh+dt@kernel.org, pmeerw@pmeerw.net, knaack.h@gmx.de, daniel.baluta@nxp.com List-Id: devicetree@vger.kernel.org On Mon, 23 Apr 2018 00:04:24 +0200 David Veenstra wrote: > A scaling factor of approximately 2 * Pi / (2^12 -1) is added, > to scale the 12-bits angular position to radians. > > A return type of IIO_VAL_INT_PLUS_NANO is used, so that the scale of > both the angle channel and angular velocity channel has 7 significant > digits. > > Signed-off-by: David Veenstra Good, will pick up with the precursors in v4. Thanks, Jonathan > --- > Changes in v3: > - A decimal approximation of the scale is used, instead > of a fractional approximation. > - Remove unneeded explanation of iio_convert_raw_to_processed. > > drivers/staging/iio/resolver/ad2s1200.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/staging/iio/resolver/ad2s1200.c b/drivers/staging/iio/resolver/ad2s1200.c > index 3e1696e52c38..d2b62308b31d 100644 > --- a/drivers/staging/iio/resolver/ad2s1200.c > +++ b/drivers/staging/iio/resolver/ad2s1200.c > @@ -60,6 +60,11 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev, > switch (m) { > case IIO_CHAN_INFO_SCALE: > switch (chan->type) { > + case IIO_ANGL: > + /* 2 * Pi / (2^12 - 1) ~= 0.001534355 */ > + *val = 0; > + *val2 = 1534355; > + return IIO_VAL_INT_PLUS_NANO; > case IIO_ANGL_VEL: > /* 2 * Pi ~= 6.283185 */ > *val = 6; > @@ -114,6 +119,7 @@ static const struct iio_chan_spec ad2s1200_channels[] = { > .indexed = 1, > .channel = 0, > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), > }, { > .type = IIO_ANGL_VEL, > .indexed = 1,