From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net ([212.227.17.22]:54663 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752227AbbGOSMm (ORCPT ); Wed, 15 Jul 2015 14:12:42 -0400 Message-ID: <55A6A295.9020102@gmx.de> Date: Wed, 15 Jul 2015 20:12:37 +0200 From: Hartmut Knaack MIME-Version: 1.0 To: Andrea Galbusera , jic23@kernel.org CC: linux-iio@vger.kernel.org Subject: Re: [PATCH 1/4] iio: adc: mcp320x: add masking of unknown bits References: <1436880983-29017-1-git-send-email-gizero@gmail.com> In-Reply-To: <1436880983-29017-1-git-send-email-gizero@gmail.com> Content-Type: text/plain; charset=US-ASCII Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org Andrea Galbusera schrieb am 14.07.2015 um 15:36: > According to the datasheet, the 2 MSBs for parts 3001 and 3201 are > unspecified and should be masked out > Hi, since resolution is already set, better make it more generic by applying the mask in _read_raw like this: *val = ret & GENMASK(adc->chip_info->resolution - 1, 0); Thanks, Hartmut > Signed-off-by: Andrea Galbusera > --- > > This was already suggested but for some reason got lost during review of a > previous patch. See http://marc.info/?l=linux-iio&m=140748835509583&w=2 > and following discussion > > drivers/iio/adc/mcp320x.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/adc/mcp320x.c b/drivers/iio/adc/mcp320x.c > index 8d9c9b9..0673ee7 100644 > --- a/drivers/iio/adc/mcp320x.c > +++ b/drivers/iio/adc/mcp320x.c > @@ -114,13 +114,13 @@ static int mcp320x_adc_conversion(struct mcp320x *adc, u8 channel, > > switch (device_index) { > case mcp3001: > - return (adc->rx_buf[0] << 5 | adc->rx_buf[1] >> 3); > + return ((adc->rx_buf[0] & 0x1f) << 5 | adc->rx_buf[1] >> 3); > case mcp3002: > case mcp3004: > case mcp3008: > return (adc->rx_buf[0] << 2 | adc->rx_buf[1] >> 6); > case mcp3201: > - return (adc->rx_buf[0] << 7 | adc->rx_buf[1] >> 1); > + return ((adc->rx_buf[0] & 0x1f) << 7 | adc->rx_buf[1] >> 1); > case mcp3202: > case mcp3204: > case mcp3208: >