From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933383AbbGJRrG (ORCPT ); Fri, 10 Jul 2015 13:47:06 -0400 Received: from mga14.intel.com ([192.55.52.115]:53383 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932454AbbGJRqz (ORCPT ); Fri, 10 Jul 2015 13:46:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,448,1432623600"; d="scan'208";a="759973912" From: "Pandruvada, Srinivas" To: "Tirdea, Irina" CC: "wsa@the-dreams.de" , "linux-kernel@vger.kernel.org" , "pmeerw@pmeerw.net" , "jic23@kernel.org" , "linux-iio@vger.kernel.org" , "linux-i2c@vger.kernel.org" Subject: Re: [PATCH v3 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler Thread-Topic: [PATCH v3 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler Thread-Index: AQHQtXNysok+kT0jC0ebwJ9MOj/gkJ3NQPyAgAg2GgCAAAN1AA== Date: Fri, 10 Jul 2015 17:46:35 +0000 Message-ID: <1436550260.2377.14.camel@spandruv-DESK3.jf.intel.com> References: <1435916017-12859-1-git-send-email-irina.tirdea@intel.com> <1435916017-12859-7-git-send-email-irina.tirdea@intel.com> <55991E2F.5020901@kernel.org> <1F3AC3675D538145B1661F571FE1805F2F068001@irsmsx105.ger.corp.intel.com> In-Reply-To: <1F3AC3675D538145B1661F571FE1805F2F068001@irsmsx105.ger.corp.intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.7.199.77] Content-Type: text/plain; charset="utf-8" Content-ID: MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id t6AHlAbI009688 On Fri, 2015-07-10 at 17:31 +0000, Tirdea, Irina wrote: > > > -----Original Message----- > > From: Jonathan Cameron [mailto:jic23@kernel.org] > > Sent: 05 July, 2015 15:08 > > To: Tirdea, Irina; Wolfram Sang; linux-iio@vger.kernel.org; linux-i2c@vger.kernel.org > > Cc: linux-kernel@vger.kernel.org; Pandruvada, Srinivas; Peter Meerwald > > Subject: Re: [PATCH v3 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler > > > > On 03/07/15 10:33, Irina Tirdea wrote: > > > 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. 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: Irina Tirdea > > Acked-by: Jonathan Cameron > > > > Thanks Jonathan! > > > Obviously you'll ideally pick up Ack's from the driver authors /maintainers > > as well. > > > > Srinivas, are you OK with these changes for bmc150, bmg160 and kxcjk-1013? > Yes. Acked-by: Srinivas Pandruvada > Thanks, > Irina > > > Jonathan > > > --- > > > drivers/iio/gyro/bmg160.c | 18 ++++++++---------- > > > 1 file changed, 8 insertions(+), 10 deletions(-) > > > > > > diff --git a/drivers/iio/gyro/bmg160.c b/drivers/iio/gyro/bmg160.c > > > index 4b423f2..04e15e9 100644 > > > --- a/drivers/iio/gyro/bmg160.c > > > +++ b/drivers/iio/gyro/bmg160.c > > > @@ -784,6 +784,7 @@ static const struct iio_event_spec bmg160_event = { > > > .sign = 's', \ > > > .realbits = 16, \ > > > .storagebits = 16, \ > > > + .endianness = IIO_LE, \ > > > }, \ > > > .event_spec = &bmg160_event, \ > > > .num_event_specs = 1 \ > > > @@ -822,19 +823,16 @@ 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 = 0; > > > > > > 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 = i2c_smbus_read_i2c_block_data_or_emulated(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); > > > > {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I