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Date: Sat, 2 Dec 2017 13:17:35 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Andreas Klinger <ak@...klinger.de>
Cc: knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
singhalsimran0@...il.com, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] iio: hx711: add triggered buffer support
On Thu, 30 Nov 2017 22:43:42 +0100
Andreas Klinger <ak@...klinger.de> wrote:
> Add buffer to device data struct and add trigger function
>
> Data format is quite simple:
> voltage - channel 0 32 Bit
> voltage - channel 1 32 Bit
> timestamp 64 Bit
>
> Using both channels at the same time is working quite slow because of
> changing the channel which needs a dummy read.
>
> Signed-off-by: Andreas Klinger <ak@...klinger.de>
Locking issues and a data positioning issue.
See inline.
Thanks,
Jonathan
> ---
> drivers/iio/adc/Kconfig | 2 +
> drivers/iio/adc/hx711.c | 106 ++++++++++++++++++++++++++++++++++++++++--------
> 2 files changed, 90 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index af4fc1279409..a83642e517d5 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -316,6 +316,8 @@ config HI8435
> config HX711
> tristate "AVIA HX711 ADC for weight cells"
> depends on GPIOLIB
> + select IIO_BUFFER
> + select IIO_TRIGGERED_BUFFER
> help
> If you say yes here you get support for AVIA HX711 ADC which is used
> for weigh cells
> diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
> index d10b9f13d557..d773fd69a76d 100644
> --- a/drivers/iio/adc/hx711.c
> +++ b/drivers/iio/adc/hx711.c
> @@ -24,6 +24,9 @@
> #include <linux/delay.h>
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> #include <linux/gpio/consumer.h>
> #include <linux/regulator/consumer.h>
>
> @@ -89,6 +92,11 @@ struct hx711_data {
> int gain_set; /* gain set on device */
> int gain_chan_a; /* gain for channel A */
> struct mutex lock;
> + /*
> + * triggered buffer
> + * 2x32-bit channel + 2x32-bit timestamp
> + */
> + u32 buffer[4];
> };
>
> static int hx711_cycle(struct hx711_data *hx711_data)
> @@ -236,34 +244,43 @@ static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
> return 0;
> }
>
> +static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
> +{
> + int ret;
> + int val;
> +
> + /*
> + * hx711_reset() must be called from here
> + * because it could be calling hx711_read() by itself
> + */
> + if (hx711_reset(hx711_data)) {
Mutex unlocks but no lock in a function is an issue...
Also I think you'll just be unlocking twice.
> + mutex_unlock(&hx711_data->lock);
> + dev_err(hx711_data->dev, "reset failed!");
> + return -EIO;
> + }
> +
> + ret = hx711_set_gain_for_channel(hx711_data, chan);
> + if (ret < 0) {
> + mutex_unlock(&hx711_data->lock);
> + return ret;
> + }
> +
> + val = hx711_read(hx711_data);
> +
> + return val;
> +}
> +
> static int hx711_read_raw(struct iio_dev *indio_dev,
> const struct iio_chan_spec *chan,
> int *val, int *val2, long mask)
> {
> struct hx711_data *hx711_data = iio_priv(indio_dev);
> - int ret;
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> mutex_lock(&hx711_data->lock);
>
> - /*
> - * hx711_reset() must be called from here
> - * because it could be calling hx711_read() by itself
> - */
> - if (hx711_reset(hx711_data)) {
> - mutex_unlock(&hx711_data->lock);
> - dev_err(hx711_data->dev, "reset failed!");
> - return -EIO;
> - }
> -
> - ret = hx711_set_gain_for_channel(hx711_data, chan->channel);
> - if (ret < 0) {
> - mutex_unlock(&hx711_data->lock);
> - return ret;
> - }
> -
> - *val = hx711_read(hx711_data);
> + *val = hx711_reset_read(hx711_data, chan->channel);
>
> mutex_unlock(&hx711_data->lock);
>
> @@ -339,6 +356,35 @@ static int hx711_write_raw_get_fmt(struct iio_dev *indio_dev,
> return IIO_VAL_INT_PLUS_NANO;
> }
>
> +static irqreturn_t hx711_trigger(int irq, void *p)
> +{
> + struct iio_poll_func *pf = p;
> + struct iio_dev *indio_dev = pf->indio_dev;
> + struct hx711_data *hx711_data = iio_priv(indio_dev);
> + int i;
> +
> + mutex_lock(&hx711_data->lock);
> +
> + memset(hx711_data->buffer, 0, sizeof(hx711_data->buffer));
> +
> + for (i = 0; i < indio_dev->masklength; i++) {
> + if (!test_bit(i, indio_dev->active_scan_mask))
> + continue;
Expectation of IIO is that if you had only the second channel on it's
data would be found at the 0 position in the buffer.
> +
> + hx711_data->buffer[i] = hx711_reset_read(hx711_data,
> + indio_dev->channels[i].channel);
> + }
> +
> + iio_push_to_buffers_with_timestamp(indio_dev, hx711_data->buffer,
> + pf->timestamp);
> +
> + mutex_unlock(&hx711_data->lock);
> +
> + iio_trigger_notify_done(indio_dev->trig);
> +
> + return IRQ_HANDLED;
> +}
> +
> static ssize_t hx711_scale_available_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> @@ -387,6 +433,14 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
> .indexed = 1,
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> + .scan_index = 0,
> + .scan_type = {
> + .sign = 'u',
> + .realbits = 24,
> + .storagebits = 32,
> + .shift = 0,
> + .endianness = IIO_CPU,
> + },
> },
> {
> .type = IIO_VOLTAGE,
> @@ -394,7 +448,16 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
> .indexed = 1,
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> + .scan_index = 1,
> + .scan_type = {
> + .sign = 'u',
> + .realbits = 24,
> + .storagebits = 32,
> + .shift = 0,
> + .endianness = IIO_CPU,
> + },
> },
> + IIO_CHAN_SOFT_TIMESTAMP(2),
> };
>
> static int hx711_probe(struct platform_device *pdev)
> @@ -482,6 +545,13 @@ static int hx711_probe(struct platform_device *pdev)
> indio_dev->channels = hx711_chan_spec;
> indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec);
>
> + ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
> + iio_pollfunc_store_time, hx711_trigger, NULL);
> + if (ret < 0) {
> + dev_err(dev, "setup of iio triggered buffer failed\n");
> + return ret;
> + }
> +
> ret = iio_device_register(indio_dev);
> if (ret < 0) {
> dev_err(dev, "Couldn't register the device\n");
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