> -----Original Message-----
> From: Jonathan Cameron [mailto:ji...@kernel.org]
> Sent: 05 July, 2015 15:08
> To: Tirdea, Irina; Wolfram Sang; linux-...@vger.kernel.org;
> linux-i2c@vger.kernel.org
> Cc: linux-ker...@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 <irina.tir...@intel.com>
> Acked-by: Jonathan Cameron <ji...@kernel.org>
>
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?
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);
> >
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