From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757189AbbA2NQz (ORCPT ); Thu, 29 Jan 2015 08:16:55 -0500 Received: from mga14.intel.com ([192.55.52.115]:20358 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753209AbbA2NQy (ORCPT ); Thu, 29 Jan 2015 08:16:54 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,486,1418112000"; d="scan'208";a="644466631" From: Irina Tirdea To: Jonathan Cameron , linux-iio@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Srinivas Pandruvada , Irina Tirdea Subject: [PATCH] iio: gyro: bmg160: optimize i2c transfers in trigger handler Date: Thu, 29 Jan 2015 15:15:52 +0200 Message-Id: <1422537352-1374-1-git-send-email-irina.tirdea@intel.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some i2c busses (e.g.: Synopsys DesignWare I2C adapter) need to enable/disable the bus at each i2c transfer and must wait for the enable/disable to happen before sending the data. When reading data in the trigger handler, the bmg160 driver does one i2c transfer for each axis. This has an impact on the frequency of the gyroscope at high sample rates due to additional delays introduced by the i2c bus at each transfer. Reading all axis values in one i2c transfer reduces the delays introduced by the i2c bus. Signed-off-by: Irina Tirdea Reviewed-by: Srinivas Pandruvada --- drivers/iio/gyro/bmg160.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/drivers/iio/gyro/bmg160.c b/drivers/iio/gyro/bmg160.c index 60451b3..814eb20 100644 --- a/drivers/iio/gyro/bmg160.c +++ b/drivers/iio/gyro/bmg160.c @@ -115,6 +115,7 @@ enum bmg160_axis { AXIS_X, AXIS_Y, AXIS_Z, + AXIS_MAX, }; static const struct { @@ -820,20 +821,21 @@ static irqreturn_t bmg160_trigger_handler(int irq, void *p) struct iio_dev *indio_dev = pf->indio_dev; struct bmg160_data *data = iio_priv(indio_dev); int bit, ret, i = 0; + s16 values[AXIS_MAX]; mutex_lock(&data->mutex); - for_each_set_bit(bit, indio_dev->buffer->scan_mask, - indio_dev->masklength) { - ret = i2c_smbus_read_word_data(data->client, - BMG160_AXIS_TO_REG(bit)); - if (ret < 0) { - mutex_unlock(&data->mutex); - goto err; - } - data->buffer[i++] = ret; + ret = i2c_smbus_read_i2c_block_data(data->client, BMG160_REG_XOUT_L, + sizeof(values), (u8 *) values); + if (ret < 0) { + mutex_unlock(&data->mutex); + goto err; } mutex_unlock(&data->mutex); + for_each_set_bit(bit, indio_dev->buffer->scan_mask, + indio_dev->masklength) + data->buffer[i++] = values[bit]; + iio_push_to_buffers_with_timestamp(indio_dev, data->buffer, data->timestamp); err: -- 1.9.1