From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ppsw-50.csi.cam.ac.uk ([131.111.8.150]:48917 "EHLO ppsw-50.csi.cam.ac.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752300Ab1D2MCz (ORCPT ); Fri, 29 Apr 2011 08:02:55 -0400 Message-ID: <4DBAA976.1050407@cam.ac.uk> Date: Fri, 29 Apr 2011 13:05:10 +0100 From: Jonathan Cameron MIME-Version: 1.0 To: michael.hennerich@analog.com CC: linux-iio@vger.kernel.org, drivers@analog.com, device-drivers-devel@blackfin.uclinux.org Subject: Re: [PATCH 1/6] IIO: GYRO: ADXRS450: Don't issue two messages, use two transfers References: <1304074721-18159-1-git-send-email-michael.hennerich@analog.com> In-Reply-To: <1304074721-18159-1-git-send-email-michael.hennerich@analog.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 04/29/11 11:58, michael.hennerich@analog.com wrote: > From: Michael Hennerich > > Don't issue the same message twice, use two transfers and group them together > > Signed-off-by: Michael Hennerich Acked-by: Jonathan Cameron > --- > drivers/staging/iio/gyro/adxrs450_core.c | 58 ++++++++++++++--------------- > 1 files changed, 28 insertions(+), 30 deletions(-) > > diff --git a/drivers/staging/iio/gyro/adxrs450_core.c b/drivers/staging/iio/gyro/adxrs450_core.c > index dcd88ff..a1a71b7 100644 > --- a/drivers/staging/iio/gyro/adxrs450_core.c > +++ b/drivers/staging/iio/gyro/adxrs450_core.c > @@ -40,29 +40,28 @@ static int adxrs450_spi_read_reg_16(struct device *dev, > struct iio_dev *indio_dev = dev_get_drvdata(dev); > struct adxrs450_state *st = iio_dev_get_devdata(indio_dev); > int ret; > - struct spi_transfer xfers = { > - .tx_buf = st->tx, > - .rx_buf = st->rx, > - .bits_per_word = 8, > - .len = 4, > + struct spi_transfer xfers[] = { > + { > + .tx_buf = st->tx, > + .bits_per_word = 8, > + .len = 4, > + .cs_change = 1, > + }, { > + .rx_buf = st->rx, > + .bits_per_word = 8, > + .len = 4, > + }, > }; > - /* Needs to send the command twice to get the wanted value */ > + > mutex_lock(&st->buf_lock); > - st->tx[0] = ADXRS450_READ_DATA | reg_address >> 7; > + st->tx[0] = ADXRS450_READ_DATA | (reg_address >> 7); > st->tx[1] = reg_address << 1; > st->tx[2] = 0; > st->tx[3] = 0; > - spi_message_init(&msg); > - spi_message_add_tail(&xfers, &msg); > - ret = spi_sync(st->us, &msg); > - if (ret) { > - dev_err(&st->us->dev, "problem while reading 16 bit register 0x%02x\n", > - reg_address); > - goto error_ret; > - } > > spi_message_init(&msg); > - spi_message_add_tail(&xfers, &msg); > + spi_message_add_tail(&xfers[0], &msg); > + spi_message_add_tail(&xfers[1], &msg); > ret = spi_sync(st->us, &msg); > if (ret) { > dev_err(&st->us->dev, "problem while reading 16 bit register 0x%02x\n", > @@ -125,11 +124,17 @@ static int adxrs450_spi_sensor_data(struct device *dev, u16 *val) > struct iio_dev *indio_dev = dev_get_drvdata(dev); > struct adxrs450_state *st = iio_dev_get_devdata(indio_dev); > int ret; > - struct spi_transfer xfers = { > - .tx_buf = st->tx, > - .rx_buf = st->rx, > - .bits_per_word = 8, > - .len = 4, > + struct spi_transfer xfers[] = { > + { > + .tx_buf = st->tx, > + .bits_per_word = 8, > + .len = 4, > + .cs_change = 1, > + }, { > + .rx_buf = st->rx, > + .bits_per_word = 8, > + .len = 4, > + }, > }; > > mutex_lock(&st->buf_lock); > @@ -139,15 +144,8 @@ static int adxrs450_spi_sensor_data(struct device *dev, u16 *val) > st->tx[3] = 0; > > spi_message_init(&msg); > - spi_message_add_tail(&xfers, &msg); > - ret = spi_sync(st->us, &msg); > - if (ret) { > - dev_err(&st->us->dev, "Problem while reading sensor data\n"); > - goto error_ret; > - } > - > - spi_message_init(&msg); > - spi_message_add_tail(&xfers, &msg); > + spi_message_add_tail(&xfers[0], &msg); > + spi_message_add_tail(&xfers[1], &msg); > ret = spi_sync(st->us, &msg); > if (ret) { > dev_err(&st->us->dev, "Problem while reading sensor data\n"); > -- > 1.6.0.2 > > >