Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756042AbbBPSOk (ORCPT ); Mon, 16 Feb 2015 13:14:40 -0500 Received: from mga14.intel.com ([192.55.52.115]:56472 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753942AbbBPSOj (ORCPT ); Mon, 16 Feb 2015 13:14:39 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,589,1418112000"; d="scan'208";a="686461115" From: Irina Tirdea To: Jonathan Cameron , linux-iio@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Srinivas Pandruvada , Adriana Reus , Irina Tirdea Subject: [PATCH v2 2/2] iio: gyro: bmg160: optimize i2c transfers in trigger handler Date: Mon, 16 Feb 2015 20:14:10 +0200 Message-Id: <1424110450-16398-3-git-send-email-irina.tirdea@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1424110450-16398-1-git-send-email-irina.tirdea@intel.com> References: <1424110450-16398-1-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: 3534 Lines: 114 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. In case i2c block read is not supported, fallback to reading each axis as a separate word. Signed-off-by: Irina Tirdea Reviewed-by: Srinivas Pandruvada --- drivers/iio/gyro/bmg160.c | 45 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 35 insertions(+), 10 deletions(-) diff --git a/drivers/iio/gyro/bmg160.c b/drivers/iio/gyro/bmg160.c index 6ccf333..9720cd6 100644 --- a/drivers/iio/gyro/bmg160.c +++ b/drivers/iio/gyro/bmg160.c @@ -109,6 +109,8 @@ struct bmg160_data { bool dready_trigger_on; bool motion_trigger_on; int64_t timestamp; + s32 (*read_block_data)(const struct i2c_client *client, u8 command, + u8 length, u8 *values); }; enum bmg160_axis { @@ -136,6 +138,23 @@ static const struct { { 133, BMG160_RANGE_250DPS}, { 66, BMG160_RANGE_125DPS} }; +static s32 bmg160_read_block_data(const struct i2c_client *client, + u8 command, u8 length, u8 *values) +{ + s32 data; + u8 i; + + for (i = 0; i < length; i += 2) { + data = i2c_smbus_read_word_data(client, command + i); + if (data < 0) + return data; + + values[i] = data & 0xFF; + values[i+1] = data >> 8; + } + return i; +} + static int bmg160_set_mode(struct bmg160_data *data, u8 mode) { int ret; @@ -822,19 +841,14 @@ static irqreturn_t bmg160_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct bmg160_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 = 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 = data->read_block_data(data->client, BMG160_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); @@ -1039,6 +1053,11 @@ static int bmg160_probe(struct i2c_client *client, int ret; const char *name = NULL; + if (!i2c_check_functionality(client->adapter, + I2C_FUNC_SMBUS_BYTE_DATA | + I2C_FUNC_SMBUS_READ_WORD_DATA)) + return -ENODEV; + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); if (!indio_dev) return -ENOMEM; @@ -1051,6 +1070,12 @@ static int bmg160_probe(struct i2c_client *client, if (ret < 0) return ret; + if (i2c_check_functionality(client->adapter, + I2C_FUNC_SMBUS_READ_I2C_BLOCK)) + data->read_block_data = i2c_smbus_read_i2c_block_data; + else + data->read_block_data = bmg160_read_block_data; + mutex_init(&data->mutex); if (id) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/