From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:51878 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752524AbdHTLFV (ORCPT ); Sun, 20 Aug 2017 07:05:21 -0400 Date: Sun, 20 Aug 2017 11:58:47 +0100 From: Jonathan Cameron To: Akinobu Mita Cc: linux-iio@vger.kernel.org, Daniel Baluta Subject: Re: [PATCH v2 07/11] iio: adc: ti-ads1015: remove unnecessary config register update Message-ID: <20170820115847.6e5be80f@archlinux> In-Reply-To: <1500564267-8613-8-git-send-email-akinobu.mita@gmail.com> References: <1500564267-8613-1-git-send-email-akinobu.mita@gmail.com> <1500564267-8613-8-git-send-email-akinobu.mita@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On Fri, 21 Jul 2017 00:24:23 +0900 Akinobu Mita wrote: > The ti-ads1015 driver has eight iio voltage channels and each iio channel > can hold own scale information. > > The ADS1015 device only have a single config register which contains an > input multiplexer selection, PGA and data rate settings. So the driver > should load the correct settings when the input multiplexer selection is > changed. > > However, regardless of which channlel is currently selected, changing any > iio channel's scale information immediately overwrites the current PGA > setting in the config register. > > It is harmless because the correct PGA settings are reloaded just before > getting adc result anyway. But it is unnecessary register update and > should be removed. > > Cc: Daniel Baluta > Cc: Jonathan Cameron > Signed-off-by: Akinobu Mita Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders to play with it. Thanks, Jonathan > --- > drivers/iio/adc/ti-ads1015.c | 18 ++++-------------- > 1 file changed, 4 insertions(+), 14 deletions(-) > > diff --git a/drivers/iio/adc/ti-ads1015.c b/drivers/iio/adc/ti-ads1015.c > index 9c501e5..e83cebc 100644 > --- a/drivers/iio/adc/ti-ads1015.c > +++ b/drivers/iio/adc/ti-ads1015.c > @@ -312,28 +312,18 @@ static int ads1015_set_scale(struct ads1015_data *data, > struct iio_chan_spec const *chan, > int scale, int uscale) > { > - int i, ret, rindex = -1; > + int i; > int fullscale = div_s64((scale * 1000000LL + uscale) << > (chan->scan_type.realbits - 1), 1000000); > > for (i = 0; i < ARRAY_SIZE(ads1015_fullscale_range); i++) { > if (ads1015_fullscale_range[i] == fullscale) { > - rindex = i; > - break; > + data->channel_data[chan->address].pga = i; > + return 0; > } > } > - if (rindex < 0) > - return -EINVAL; > - > - ret = regmap_update_bits(data->regmap, ADS1015_CFG_REG, > - ADS1015_CFG_PGA_MASK, > - rindex << ADS1015_CFG_PGA_SHIFT); > - if (ret < 0) > - return ret; > - > - data->channel_data[chan->address].pga = rindex; > > - return 0; > + return -EINVAL; > } > > static int ads1015_set_data_rate(struct ads1015_data *data, int chan, int rate)