From: Eva Rachel Retuya <eraretuya@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: linux-iio@vger.kernel.org, knaack.h@gmx.de, lars@metafoo.de,
pmeerw@pmeerw.net, dmitry.torokhov@gmail.com,
michael.hennerich@analog.com, daniel.baluta@gmail.com,
amsfield22@gmail.com, florian.vaussard@heig-vd.ch,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/4] iio: accel: adxl345_core: Introduce set_mode and data_ready functions
Date: Tue, 2 May 2017 19:39:03 +0800 [thread overview]
Message-ID: <20170502113902.GA3030@Socrates-UM> (raw)
In-Reply-To: <652e2497-d091-9468-a4ee-983bcc626d6b@kernel.org>
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);
> >
> >
>
next prev parent reply other threads:[~2017-05-02 11:39 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-29 7:48 [PATCH v2 0/4] iio: accel: adxl345: Add support for buffered readings Eva Rachel Retuya
2017-04-29 7:48 ` [PATCH v2 1/4] dt-bindings: iio: accel: adxl345: Add optional interrupt-names support Eva Rachel Retuya
2017-04-29 7:48 ` [PATCH v2 2/4] iio: accel: adxl345_core: Introduce set_mode and data_ready functions Eva Rachel Retuya
2017-05-01 0:22 ` Jonathan Cameron
2017-05-01 19:42 ` Andy Shevchenko
2017-05-01 19:48 ` Jonathan Cameron
2017-05-01 20:07 ` Andy Shevchenko
2017-05-01 20:18 ` Jonathan Cameron
2017-05-02 11:39 ` Eva Rachel Retuya [this message]
2017-05-02 16:32 ` Jonathan Cameron
2017-05-10 13:07 ` Eva Rachel Retuya
2017-05-01 11:21 ` Andy Shevchenko
2017-05-02 11:46 ` Eva Rachel Retuya
2017-04-29 7:49 ` [PATCH v2 3/4] iio: accel: adxl345: Setup DATA_READY trigger Eva Rachel Retuya
2017-05-01 0:32 ` Jonathan Cameron
2017-05-02 3:01 ` Rob Herring
2017-05-02 15:59 ` Jonathan Cameron
2017-05-10 14:33 ` Eva Rachel Retuya
2017-05-02 11:59 ` Eva Rachel Retuya
2017-05-01 11:31 ` Andy Shevchenko
2017-05-02 12:15 ` Eva Rachel Retuya
2017-05-02 21:05 ` Andy Shevchenko
2017-05-10 13:24 ` Eva Rachel Retuya
2017-05-14 15:15 ` Jonathan Cameron
2017-05-14 16:08 ` Dmitry Torokhov
2017-05-05 18:26 ` Jonathan Cameron
2017-05-10 13:31 ` Eva Rachel Retuya
2017-04-29 7:49 ` [PATCH v2 4/4] iio: accel: adxl345: Add support for triggered buffer Eva Rachel Retuya
2017-05-01 0:42 ` Jonathan Cameron
2017-05-02 12:23 ` Eva Rachel Retuya
2017-05-02 16:08 ` Jonathan Cameron
2017-05-01 11:24 ` Andy Shevchenko
2017-05-02 12:24 ` Eva Rachel Retuya
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