On 30/01/15 04:03, Viorel Suman wrote: > Hi, > > You might need more space in "values" buffer, for more details please check the > "iio_push_to_buffers_with_timestamp" description and implementation. Whilst that function is a little 'odd', this patch doesn't change the use of buffer (simply how it if filled). The buffer is 16bytes long (8 x s16) so should be fine (4 x 16 bit and 1 x 64 bit). More problematically, we have using a new smbus capability here (to read it one transaction). It's one you can check for, so I'm guessing we aren't guaranteed it is present. I2C_FUNC_SMBUS_READ_I2C_BLOCK Jonathan > > Regards, > Viorel > > > On Thu, Jan 29, 2015 at 3:15 PM, Irina Tirdea <irina.tirdea@xxxxxxxxx <mailto:irina.tirdea@xxxxxxxxx>> 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. > > Signed-off-by: Irina Tirdea <irina.tirdea@xxxxxxxxx <mailto:irina.tirdea@xxxxxxxxx>> > Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx <mailto:srinivas.pandruvada@xxxxxxxxxxxxxxx>> > --- > 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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@xxxxxxxxxxxxxxx <mailto:majordomo@xxxxxxxxxxxxxxx> > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
