On 24/03/16 09:29, 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 bmc150 accel driver does
> one bus transfer for each axis. This has an impact on the frequency
> of the accelerometer at high sample rates due to additional delays
> introduced by the bus at each transfer.
>
> Reading all axis values in one bus transfer reduces the delays
> introduced by the bus.
>
> Signed-off-by: Irina Tirdea <irina.tir...@intel.com>
I forgot to highlight on the earlier driver that there is also 'technically'
a bit of an ABI change here because we are now exporting as LE rather than CPU
order. However, I 'hope' anyone actually accessing the buffered data is either
doing it through a nice library or hasn't hacked the endian unwinding out of
the generic_buffer example!
Again, fingers crossed this doesn't break anything significant.
Applied,
Thanks,
Jonathan
> ---
> drivers/iio/gyro/bmg160_core.c | 17 ++++++-----------
> 1 file changed, 6 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/iio/gyro/bmg160_core.c b/drivers/iio/gyro/bmg160_core.c
> index 8d6e5b1..43570b8 100644
> --- a/drivers/iio/gyro/bmg160_core.c
> +++ b/drivers/iio/gyro/bmg160_core.c
> @@ -734,6 +734,7 @@ 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 \
> @@ -773,20 +774,14 @@ 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;
> - unsigned int val;
> + int ret;
>
> mutex_lock(&data->mutex);
> - for (bit = 0; bit < AXIS_MAX; bit++) {
> - ret = regmap_bulk_read(data->regmap, BMG160_AXIS_TO_REG(bit),
> - &val, 2);
> - if (ret < 0) {
> - mutex_unlock(&data->mutex);
> - goto err;
> - }
> - data->buffer[i++] = ret;
> - }
> + ret = regmap_bulk_read(data->regmap, BMG160_REG_XOUT_L,
> + data->buffer, AXIS_MAX * 2);
> mutex_unlock(&data->mutex);
> + if (ret < 0)
> + goto err;
>
> iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
> pf->timestamp);
>
