> -----Original Message----- > From: Jonathan Cameron [mailto:jic23@xxxxxxxxxx] > Sent: 05 July, 2015 15:08 > To: Tirdea, Irina; Wolfram Sang; linux-iio@xxxxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx; 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.tirdea@xxxxxxxxx> > Acked-by: Jonathan Cameron <jic23@xxxxxxxxxx> > 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); > > -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
