From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Cameron Subject: Re: [PATCH v2 07/13] staging: iio: ad2s1200: Improve readability with be16_to_cpup Date: Sat, 21 Apr 2018 17:55:21 +0100 Message-ID: <20180421175521.5592e47a@archlinux> References: <22b031a8baafad18c3ba2136f8d43fbb4083c1cf.1524247563.git.davidjulianveenstra@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <22b031a8baafad18c3ba2136f8d43fbb4083c1cf.1524247563.git.davidjulianveenstra@gmail.com> 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 Fri, 20 Apr 2018 21:30:32 +0200 David Veenstra wrote: > The manual states that the data is contained in the upper 12 bits > of the 16 bits read by spi. The code that extracts these 12 bits > is correct for both be and le machines, but this is not clear > from a first glance. > > To improve readability the relevant expressions are replaced > with equivalent expressions that use be16_to_cpup. > > Signed-off-by: David Veenstra > --- > drivers/staging/iio/resolver/ad2s1200.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/drivers/staging/iio/resolver/ad2s1200.c b/drivers/staging/iio/resolver/ad2s1200.c > index 0a5fc9917e32..11ed9c7332e6 100644 > --- a/drivers/staging/iio/resolver/ad2s1200.c > +++ b/drivers/staging/iio/resolver/ad2s1200.c > @@ -57,7 +57,7 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev, > { > struct ad2s1200_state *st = iio_priv(indio_dev); > int ret = 0; > - s16 vel; > + u16 vel; > > mutex_lock(&st->lock); > gpio_set_value(st->sample, 0); > @@ -73,14 +73,13 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev, > return ret; > } > > + vel = be16_to_cpup((__be16 *)st->rx); Well it isn't vel (velocity) in one case so now the name is misleading. Also that type cast suggests a fairly obvious cleanup associated with this one. Why not make st->rx a __be16 in the first pace avoiding the need to cast at all? Then you could just have *val = be16_to_cpu(st->rx) >> 4 and similar. > switch (chan->type) { > case IIO_ANGL: > - *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4); > + *val = vel >> 4; > break; > case IIO_ANGL_VEL: > - vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4); > - vel = sign_extend32(vel, 11); > - *val = vel; > + *val = sign_extend32((s16)vel >> 4, 11); If you were to use an intermediate that was s16 then the sign extend would be automatic. Perhaps it is clear to do it like this though.. Up to you. > break; > default: > mutex_unlock(&st->lock);