On Mon, May 01, 2017 at 01:22:52AM +0100, Jonathan Cameron wrote:
Hello Jonathan,
[...]
> > +static int adxl345_set_mode(struct adxl345_data *data, u8 mode)
> > +{
> > + struct device *dev = regmap_get_device(data->regmap);
> > + int ret;
> > +
> > + ret = regmap_write(data->regmap, ADXL345_REG_POWER_CTL, mode);
> > + if (ret < 0) {
> > + dev_err(dev, "Failed to set power mode, %d\n", ret);
> > + return ret;
> drop the return ret here and just return ret at the end of the function.
> One of the static checkers will probably moan about this otherwise.
OK.
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int adxl345_data_ready(struct adxl345_data *data)
> > +{
> So this is a polling the dataready bit. Will ensure we always
> get fresh data when a read occurs. Please add a comment to
> that effect as that's not always how devices work.
OK.
> > + struct device *dev = regmap_get_device(data->regmap);
> > + int tries = 5;
> > + u32 val;
> > + int ret;
> > +
> > + do {
> > + /*
> > + * 1/ODR + 1.1ms; 11.1ms at ODR of 0.10 Hz
> > + * Sensor currently operates at default ODR of 100 Hz
> > + */
> > + usleep_range(1100, 11100);
> That's a huge range to allow... I'm not following the argument for why.
> Or do we have a stray 0?
>
Not a stray 0. Range is from 1.1ms to 11.1ms, this represents the
wake-up time when going to standby/other power saving modes ->
measurement mode. I'm going to clarify the comment on why it is needed
on the next revision.
> > +
> > + ret = regmap_read(data->regmap, ADXL345_REG_INT_SOURCE, &val);
> > + if (ret < 0)
> > + return ret;
> > + if ((val & ADXL345_INT_DATA_READY) == ADXL345_INT_DATA_READY)
> > + return 0;
> > + } while (--tries);
> > + dev_err(dev, "Data is not yet ready, try again.\n");
> > +
> This is almost certainly a hardware fault. I'd be more brutal with
> the error and return -EIO. If you get here your hardware is very unlikely
> to be working correctly if you try again.
OK, will change it to -EIO then.
> > + return -EAGAIN;
> > +}
> > +
> > #define ADXL345_CHANNEL(reg, axis) {
> > \
> > .type = IIO_ACCEL, \
> > .modified = 1, \
> > @@ -72,6 +118,19 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
> >
> > switch (mask) {
> > case IIO_CHAN_INFO_RAW:
> > + mutex_lock(&data->lock);
> > + ret = adxl345_set_mode(data, ADXL345_POWER_CTL_MEASURE);
> > + if (ret < 0) {
> > + mutex_unlock(&data->lock);
> > + return ret;
> > + }
> > +
> > + ret = adxl345_data_ready(data);
> > + if (ret < 0) {
> > + adxl345_set_mode(data, ADXL345_POWER_CTL_STANDBY);
> > + mutex_unlock(&data->lock);
> What is the logic that puts the mutex_unlock here in the error case
> and before the set_mode in the normal path? Even if it doesn't
> matter make them the same as it is less likely to raise questions
> in the future!
OK, will make it consistent.
> > + return ret;
> > + }
> > /*
> > * Data is stored in adjacent registers:
> > * ADXL345_REG_DATA(X0/Y0/Z0) contain the least significant byte
> > @@ -79,10 +138,15 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
> > */
> > ret = regmap_bulk_read(data->regmap, chan->address, ®val,
> > sizeof(regval));
> > - if (ret < 0)
> > + mutex_unlock(&data->lock);
> > + if (ret < 0) {
> > + adxl345_set_mode(data, ADXL345_POWER_CTL_STANDBY);
> > return ret;
> > + }
> >
> > *val = sign_extend32(le16_to_cpu(regval), 12);
> > + adxl345_set_mode(data, ADXL345_POWER_CTL_STANDBY);
> > +
> > return IIO_VAL_INT;
> > case IIO_CHAN_INFO_SCALE:
> > *val = 0;
[...]
> > @@ -169,8 +224,7 @@ int adxl345_core_remove(struct device *dev)
> >
> > iio_device_unregister(indio_dev);
> >
> > - return regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
> > - ADXL345_POWER_CTL_STANDBY);
> > + return adxl345_set_mode(data, ADXL345_POWER_CTL_STANDBY);
> Under what circumstances would we not already be in the correct state?
> A brief comment here would be good.
I'm leaving this unremoved to catch cases where in the sensor fails to
return to standby mode after a read. Will add the said comment.
Thanks,
Eva
> > }
> > EXPORT_SYMBOL_GPL(adxl345_core_remove);
> >
> >
>
