From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752933AbcHQRp6 (ORCPT ); Wed, 17 Aug 2016 13:45:58 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33096 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752353AbcHQRp4 (ORCPT ); Wed, 17 Aug 2016 13:45:56 -0400 Date: Wed, 17 Aug 2016 10:45:54 -0700 From: Alison Schofield To: Jonathan Cameron Cc: mranostay@gmail.com, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] iio: humidity: hdc100x: fix sensor data reads of temp and humidity Message-ID: <20160817174552.GA17877@d830.WORKGROUP> References: <20160808181430.GA2852@d830.WORKGROUP> <8136e55d-1acd-cd56-e879-14877a16a43c@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8136e55d-1acd-cd56-e879-14877a16a43c@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 15, 2016 at 05:27:00PM +0100, Jonathan Cameron wrote: > On 08/08/16 19:14, Alison Schofield wrote: > > Replace the i2c_smbus_read_byte commmands used to retrieve the sensor > > data with an i2c_master_recv command. > > > > The smbus read byte method fails because the device does not expect a > > stop condition after sending the first byte. When we issue the second > > read, we are getting the first byte again. Net effect is that of the 14 > > bits used for the measurement, the 8 most significant bits are correct, > > the lower 6 are not. > > > > None of the smbus read protocols follow the pattern this device requires > > (S Addr Rd [A] Data [A] Data NA P), hence the switch to an i2c receive > > transaction. > > > > Signed-off-by: Alison Schofield > > Cc: Daniel Baluta > Hi Alison, > > Nice fix. Note that I'd have liked a fixes: tag for this one... > It's a bit fiddly as will need backporting to older stable kernels. > > I'll leave it marked for stable but with no version. As long as > it applies cleanly it should be fine. > > Applied to the fixes-togreg branch of iio.git. > > Thanks, > > Jonathan Here's the fixes tag, if you can still insert it... Fixes: 4839367d99e3 ("iio: humidity: add HDC100x support") alisons > > > --- > > Changes in v2: > > update commit message to say what this fixes > > use endian type & macro to correctly manage byte order > > use sizeof for data length > > > > drivers/iio/humidity/hdc100x.c | 27 +++++++-------------------- > > 1 file changed, 7 insertions(+), 20 deletions(-) > > > > diff --git a/drivers/iio/humidity/hdc100x.c b/drivers/iio/humidity/hdc100x.c > > index a03832a..e0c9c70 100644 > > --- a/drivers/iio/humidity/hdc100x.c > > +++ b/drivers/iio/humidity/hdc100x.c > > @@ -142,7 +142,7 @@ static int hdc100x_get_measurement(struct hdc100x_data *data, > > struct i2c_client *client = data->client; > > int delay = data->adc_int_us[chan->address]; > > int ret; > > - int val; > > + __be16 val; > > > > /* start measurement */ > > ret = i2c_smbus_write_byte(client, chan->address); > > @@ -154,26 +154,13 @@ static int hdc100x_get_measurement(struct hdc100x_data *data, > > /* wait for integration time to pass */ > > usleep_range(delay, delay + 1000); > > > > - /* > > - * i2c_smbus_read_word_data cannot() be used here due to the command > > - * value not being understood and causes NAKs preventing any reading > > - * from being accessed. > > - */ > > - ret = i2c_smbus_read_byte(client); > > + /* read measurement */ > > + ret = i2c_master_recv(data->client, (char *)&val, sizeof(val)); > > if (ret < 0) { > > - dev_err(&client->dev, "cannot read high byte measurement"); > > + dev_err(&client->dev, "cannot read sensor data\n"); > > return ret; > > } > > - val = ret << 8; > > - > > - ret = i2c_smbus_read_byte(client); > > - if (ret < 0) { > > - dev_err(&client->dev, "cannot read low byte measurement"); > > - return ret; > > - } > > - val |= ret; > > - > > - return val; > > + return be16_to_cpu(val); > > } > > > > static int hdc100x_get_heater_status(struct hdc100x_data *data) > > @@ -272,8 +259,8 @@ static int hdc100x_probe(struct i2c_client *client, > > struct iio_dev *indio_dev; > > struct hdc100x_data *data; > > > > - if (!i2c_check_functionality(client->adapter, > > - I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE)) > > + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA | > > + I2C_FUNC_SMBUS_BYTE | I2C_FUNC_I2C)) > > return -EOPNOTSUPP; > > > > indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); > > >