Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757287AbcCXJa2 (ORCPT ); Thu, 24 Mar 2016 05:30:28 -0400 Received: from mga14.intel.com ([192.55.52.115]:11670 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757121AbcCXJaA (ORCPT ); Thu, 24 Mar 2016 05:30:00 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,384,1455004800"; d="scan'208";a="72381499" From: Irina Tirdea To: Jonathan Cameron , linux-iio@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald , Octavian Purdila , Markus Pargmann , Srinivas Pandruvada , Adriana Reus , Irina Tirdea Subject: [PATCH 6/6] iio: accel: kxcjk-1013: optimize i2c transfers in trigger handler Date: Thu, 24 Mar 2016 11:29:31 +0200 Message-Id: <1458811771-25217-7-git-send-email-irina.tirdea@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1458811771-25217-1-git-send-email-irina.tirdea@intel.com> References: <1458811771-25217-1-git-send-email-irina.tirdea@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2299 Lines: 66 From: Adriana Reus 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 kxcjk-1013 accel driver does one i2c transfer for each axis. This has an impact on the frequency of the accelerometer 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. Uses i2c_smbus_read_i2c_block_data_or_emulated that will fallback to reading each axis as a separate word in case i2c block read is not supported. Signed-off-by: Adriana Reus Signed-off-by: Irina Tirdea Acked-by: Jonathan Cameron Acked-by: Srinivas Pandruvada --- drivers/iio/accel/kxcjk-1013.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c index 3861fe9..4881856 100644 --- a/drivers/iio/accel/kxcjk-1013.c +++ b/drivers/iio/accel/kxcjk-1013.c @@ -923,7 +923,7 @@ static const struct iio_event_spec kxcjk1013_event = { .realbits = 12, \ .storagebits = 16, \ .shift = 4, \ - .endianness = IIO_CPU, \ + .endianness = IIO_LE, \ }, \ .event_spec = &kxcjk1013_event, \ .num_event_specs = 1 \ @@ -961,19 +961,16 @@ static irqreturn_t kxcjk1013_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct kxcjk1013_data *data = iio_priv(indio_dev); - int bit, ret, i = 0; + int ret; mutex_lock(&data->mutex); - - for (bit = 0; bit < AXIS_MAX; bit++) { - ret = kxcjk1013_get_acc_reg(data, bit); - if (ret < 0) { - mutex_unlock(&data->mutex); - goto err; - } - data->buffer[i++] = ret; - } + ret = i2c_smbus_read_i2c_block_data_or_emulated(data->client, + KXCJK1013_REG_XOUT_L, + AXIS_MAX * 2, + (u8 *)data->buffer); mutex_unlock(&data->mutex); + if (ret < 0) + goto err; iio_push_to_buffers_with_timestamp(indio_dev, data->buffer, data->timestamp); -- 1.9.1