From mboxrd@z Thu Jan 1 00:00:00 1970 X-GM-THRID: 6845034921984 X-Received: by 10.152.6.41 with SMTP id x9mr2131857lax.10.1425633169020; Fri, 06 Mar 2015 01:12:49 -0800 (PST) X-BeenThere: outreachy-kernel@googlegroups.com Received: by 10.180.98.233 with SMTP id el9ls58147wib.8.gmail; Fri, 06 Mar 2015 01:12:48 -0800 (PST) X-Received: by 10.194.201.10 with SMTP id jw10mr2145774wjc.3.1425633168107; Fri, 06 Mar 2015 01:12:48 -0800 (PST) Return-Path: Received: from mout.kundenserver.de (mout.kundenserver.de. [212.227.126.130]) by gmr-mx.google.com with ESMTPS id by11si69319wib.1.2015.03.06.01.12.47 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 06 Mar 2015 01:12:48 -0800 (PST) Received-SPF: none (google.com: arnd@arndb.de does not designate permitted sender hosts) client-ip=212.227.126.130; Authentication-Results: gmr-mx.google.com; spf=none (google.com: arnd@arndb.de does not designate permitted sender hosts) smtp.mail=arnd@arndb.de Received: from oxbaltgw05.schlund.de ([172.19.246.11]) by mrelayeu.kundenserver.de (mreue004) with ESMTPSA (Nemesis) id 0M5Kwt-1XXrIu2F2t-00zT0E; Fri, 06 Mar 2015 10:12:47 +0100 Date: Fri, 6 Mar 2015 10:12:47 +0100 (CET) From: arnd@arndb.de Reply-To: arnd@arndb.de To: Somya Anand , outreachy-kernel Message-ID: <899581237.61503.1425633167521.JavaMail.open-xchange@oxbaltgw05.schlund.de> In-Reply-To: <1425630960-7142-1-git-send-email-somyaanand214@gmail.com> References: <1425630960-7142-1-git-send-email-somyaanand214@gmail.com> Subject: Re: [Outreachy kernel] [PATCH] Staging: iio: Change data type in adis16220_read_16bit to u16 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Priority: 3 Importance: Medium X-Mailer: Open-Xchange Mailer v7.6.0-Rev38 X-Originating-Client: open-xchange-appsuite X-Provags-ID: V03:K0:5hpaEfSCt+5TnGSSJMLPb0DHdswahljS5Uz8alRasN88i9zu6af QMC1QTrrNpM9uODqwD8+iiihk1oCTiSCUhTYXDvJ4eU7dDCFUqKcMkVRahtc2RK9wu+kJvY hZcdMuKMWV7zHyh0GOIie5f+5jqnlOE/+MTfdO93Un/wRukk396J2YTd456htavEai9/pVh bZjqLTTfgQEYhMTPPzzug== X-UI-Out-Filterresults: notjunk:1; > Somya Anand hat am 6. M=C3=A4rz 2015 um 09:36 > geschrieben: > diff --git a/drivers/staging/iio/accel/adis16220_core.c > b/drivers/staging/iio/accel/adis16220_core.c > index d478f51..7a4a0fd 100644 > --- a/drivers/staging/iio/accel/adis16220_core.c > +++ b/drivers/staging/iio/accel/adis16220_core.c > @@ -28,16 +28,15 @@ static ssize_t adis16220_read_16bit(struct device *de= v, > struct iio_dev *indio_dev =3D dev_to_iio_dev(dev); > struct adis16220_state *st =3D iio_priv(indio_dev); > ssize_t ret; > - s16 val =3D 0; > + u16 val =3D 0; > =20 > /* Take the iio_dev status lock */ > mutex_lock(&indio_dev->mlock); In a patch like this, it would be best to also drop the initialization to z= ero, which is not used here. Not initializing it helps the compiler provide useful warnin= gs if the code gets changed to return an otherwise uninitialized result. > - ret =3D adis_read_reg_16(&st->adis, this_attr->address, > - (u16 *)&val); > + ret =3D adis_read_reg_16(&st->adis, this_attr->address, &val); > mutex_unlock(&indio_dev->mlock); > if (ret) > return ret; > - return sprintf(buf, "%d\n", val); > + return sprintf(buf, "%u\n", val); > } > =20 This looks wrong: Unless you know better, you should assume that the sprint= f format string is correct and that the value is indeed signed for the purpose of th= is file. The reason why adis_read_reg_16() takes a u16 argument instead of s16 is th= at it accesses a register that doesn't have a concept of signedness. I would just leave the code as it is, alternatively you could have two variables and explicitl= y cast from u16 to s16 with a comment. Arnd