On 28/03/16 11:09, Peter Meerwald-Stadler 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
>
> should refer to bmg160
Good spot. It's also a gyroscope, not an accelerometer... I just fixed this
up and repushed out testing.
>
>>> 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.tirdea@xxxxxxxxx>
>> 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!
>
> the patch takes away the possibility to do buffered reads on individual
> channels (not sure if this is useful per se)
>
> this optimizes for the common case, ok;
>
> wondering if adding
> .endianness = IIO_LE
> is actually an unrelated fix
Good point, when I first read the code I assumed we were moving from an i2c_word
read to a bulk read, thus necessitating this addition. However, we aren't as it
was previously as an i2c_bulk read of 2 bytes...
Irina, could you confirm if this was broken before your patches?
I'll leave this as is, perhaps we need an additional fix patch specifying LE to
put out as a fix.
>
>> 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);
>>>
>>
>
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