From: Jonathan Cameron <jic23@kernel.org>
To: 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 4/4] iio: accel: adxl345: Add support for triggered buffer
Date: Tue, 2 May 2017 17:08:52 +0100 [thread overview]
Message-ID: <19696c7f-a7c5-05d9-c58c-9a1d3588e75a@kernel.org> (raw)
In-Reply-To: <20170502122340.GE3030@Socrates-UM>
On 02/05/17 13:23, Eva Rachel Retuya wrote:
> On Mon, May 01, 2017 at 01:42:29AM +0100, Jonathan Cameron wrote:
> [...]
>> Few minor bits inline... I'm a little bit in two minds about the
>> holding up waiting for new data when using another trigger...
>>
>> Jonathan
> [...]
>>> static int adxl345_read_raw(struct iio_dev *indio_dev,
>>> @@ -127,6 +151,10 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
>>>
>>> switch (mask) {
>>> case IIO_CHAN_INFO_RAW:
>>> + ret = iio_device_claim_direct_mode(indio_dev);
>>> + if (ret)
>>> + return ret;
>>> +
>>> mutex_lock(&data->lock);
>>> ret = adxl345_set_mode(data, ADXL345_POWER_CTL_MEASURE);
>>> if (ret < 0) {
>>> @@ -148,12 +176,14 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
>>> ret = regmap_bulk_read(data->regmap, chan->address, ®val,
>>> sizeof(regval));
>>> mutex_unlock(&data->lock);
>>> + iio_device_release_direct_mode(indio_dev);
>>> if (ret < 0) {
>>> adxl345_set_mode(data, ADXL345_POWER_CTL_STANDBY);
>>> return ret;
>>> }
>>>
>>> - *val = sign_extend32(le16_to_cpu(regval), 12);
>>> + *val = sign_extend32(le16_to_cpu(regval),
>>> + chan->scan_type.realbits - 1)
>> This change isn't really needed, but I suppose it does little harm...
>>
>>> adxl345_set_mode(data, ADXL345_POWER_CTL_STANDBY);
>>>
>>> return IIO_VAL_INT;
>>> @@ -186,6 +216,64 @@ static irqreturn_t adxl345_irq(int irq, void *p)
>>> return IRQ_NONE;
>>> }
>>>
>>> +static irqreturn_t adxl345_trigger_handler(int irq, void *p)
>>> +{
>>> + struct iio_poll_func *pf = p;
>>> + struct iio_dev *indio_dev = pf->indio_dev;
>>> + struct adxl345_data *data = iio_priv(indio_dev);
>>> + int ret;
>>> +
>>> + mutex_lock(&data->lock);
>>> + /* Make sure data is ready when using external trigger */
>> I 'think' this is only really relevant for the very first one.
>> After that general rule of thumb is that if an external trigger
>> is too quick - bad luck you'll get repeated data.
>>
>> One of the reasons we would want to use another trigger is to
>> support capture in parallel from several sensors - if we 'hold'
>> like this we'll get out of sync.
>>
>> As such I wonder if a better strategy would be to 'hold' for the
>> first reading in the buffer enable - thus guaranteeing valid
>> data before we start. After that we wouldn't need to check this
>> here.
>>
>
> Thanks for the explanation. If we are to go with this one, where to put
> it, preenable or postenable? I'm assuming the latter but would like to
> confirm.
postenable. It could in theory be effected by a future use of the
update_scan_mode callback so should be after that.
J
>
>> What do others think?
>>
>
> Any other inputs are greatly appreciated.
>
> Eva
> --
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>
next prev parent reply other threads:[~2017-05-02 16:08 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
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 [this message]
2017-05-01 11:24 ` Andy Shevchenko
2017-05-02 12:24 ` Eva Rachel Retuya
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