On 25/11/15 11:28, Marc Titinger wrote:
> This can lead to repeated or skipped samples depending on the clock beat
> between the capture thread and the chip sampling clock, but will also spare
> reading/waiting for the Capture Ready Flag and improve the available i2c
> bandwidth for reading measurements.
>
> Output of iio_info:
> ...snip...
> 4 device-specific attributes found:
> attr 0: in_oversampling_ratio value: 4
> attr 1: in_allow_async_readout value: 0
> attr 2: integration_time_available value: 140 204 332 588 1100 2116 4156
> 8244
> attr 3: in_sampling_frequency value: 114
>
This is a good compromise if it is needed to get the rates as high as
you need.
One suggestion inline.
Jonathan
> Signed-off-by: Marc Titinger <mtitin...@baylibre.com>
> ---
> drivers/iio/adc/ina2xx-iio.c | 48
> ++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 42 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/adc/ina2xx-iio.c b/drivers/iio/adc/ina2xx-iio.c
> index 4a0026c..c153164 100644
> --- a/drivers/iio/adc/ina2xx-iio.c
> +++ b/drivers/iio/adc/ina2xx-iio.c
> @@ -114,6 +114,7 @@ struct ina2xx_chip_info {
> int avg;
> int itb; /* Bus voltage integration time uS */
> int its; /* Shunt voltage integration tim uS */
> + bool allow_async_readout;
> };
>
> static const struct ina2xx_config ina2xx_config[] = {
> @@ -335,6 +336,33 @@ _err:
> }
>
>
> +static ssize_t ina2xx_allow_async_readout_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));
> +
> + return sprintf(buf, "%d\n", chip->allow_async_readout);
> +}
> +
> +static ssize_t ina2xx_allow_async_readout_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t len)
> +{
> + struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));
> + unsigned long val;
> + int ret;
> +
strtobool would simplify this.
> + ret = kstrtoul((const char *) buf, 10, &val);
> + if (ret)
> + return -EINVAL;
> +
> + chip->allow_async_readout = !!val;
> +
> + return len;
> +}
> +
> +
> #define INA2XX_CHAN(_type, _index, _address) { \
> .type = _type, \
> .address = _address, \
> @@ -402,11 +430,12 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
> * GPIO a triggered buffer could be used instead.
> * For now, we pay for that extra read of the ALERT register
> */
> - do {
> - ret = regmap_read(chip->regmap, INA226_ALERT_MASK,
> - &alert);
> - if (ret < 0)
> - goto _err;
> + if (!chip->allow_async_readout)
> + do {
> + ret = regmap_read(chip->regmap, INA226_ALERT_MASK,
> + &alert);
> + if (ret < 0)
> + goto _err;
>
> alert &= INA266_CVRF;
> trace_printk("Conversion ready: %d\n", !!alert);
> @@ -457,7 +486,8 @@ static int ina2xx_capture_thread(void *data)
> * Poll a bit faster than the chip internal Fs, in case
> * we wish to sync with the conversion ready flag.
> */
> - sampling_us -= 200;
> + if (!chip->allow_async_readout)
> + sampling_us -= 200;
>
> do {
> buffer_us = ina2xx_work_buffer(indio_dev);
> @@ -480,6 +510,7 @@ int ina2xx_buffer_enable(struct iio_dev *indio_dev)
> 1000000/sampling_us, chip->avg);
>
> trace_printk("Expected work period: %u us\n", sampling_us);
> + trace_printk("Async readout mode: %d\n", chip->allow_async_readout);
>
> prev_ns = iio_get_time_ns();
>
> @@ -519,7 +550,12 @@ static int ina2xx_debug_reg(struct iio_dev *indio_dev,
> /* frequencies matching the cummulated integration times for vshunt and vbus
> */
> static IIO_CONST_ATTR_INT_TIME_AVAIL("140 204 332 588 1100 2116 4156 8244");
>
> +static IIO_DEVICE_ATTR(in_allow_async_readout, S_IRUGO | S_IWUSR,
> + ina2xx_allow_async_readout_show,
> + ina2xx_allow_async_readout_store, 0);
> +
> static struct attribute *ina2xx_attributes[] = {
> + &iio_dev_attr_in_allow_async_readout.dev_attr.attr,
> &iio_const_attr_integration_time_available.dev_attr.attr,
> NULL,
> };
>
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