The iio timestamp clock is user selectable and may be non-monotonic. Also,
only part of the acquisition time is measured, thus the delay was longer
than intended.
Signed-off-by: Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx>
---
drivers/iio/adc/ina2xx-adc.c | 35 +++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 14 deletions(-)
diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 2621a34ee5c6..65bd9e69faf2 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -703,10 +703,10 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
/* data buffer needs space for channel data and timestap */
unsigned short data[4 + sizeof(s64)/sizeof(short)];
int bit, ret, i = 0;
- s64 time_a, time_b;
+ s64 time;
unsigned int alert;
- time_a = iio_get_time_ns(indio_dev);
+ time = iio_get_time_ns(indio_dev);
/*
* Because the timer thread and the chip conversion clock
@@ -752,11 +752,9 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
data[i++] = val;
}
- time_b = iio_get_time_ns(indio_dev);
+ iio_push_to_buffers_with_timestamp(indio_dev, data, time);
- iio_push_to_buffers_with_timestamp(indio_dev, data, time_a);
-
- return (unsigned long)(time_b - time_a) / 1000;
+ return 0;
};
static int ina2xx_capture_thread(void *data)
@@ -764,7 +762,9 @@ static int ina2xx_capture_thread(void *data)
struct iio_dev *indio_dev = data;
struct ina2xx_chip_info *chip = iio_priv(indio_dev);
int sampling_us = SAMPLING_PERIOD(chip);
- int buffer_us, delay_us;
+ int ret;
+ struct timespec64 next, now, delta;
+ s64 delay_us;
/*
* Poll a bit faster than the chip internal Fs, in case
@@ -773,15 +773,22 @@ static int ina2xx_capture_thread(void *data)
if (!chip->allow_async_readout)
sampling_us -= 200;
+ ktime_get_ts64(&next);
+
do {
- buffer_us = ina2xx_work_buffer(indio_dev);
- if (buffer_us < 0)
- return buffer_us;
+ ret = ina2xx_work_buffer(indio_dev);
+ if (ret < 0)
+ return ret;
- if (sampling_us > buffer_us) {
- delay_us = sampling_us - buffer_us;
- usleep_range(delay_us, (delay_us * 3) >> 1);
- }
+ ktime_get_ts64(&now);
+
+ do {
+ timespec64_add_ns(&next, 1000 * sampling_us);
+ delta = timespec64_sub(next, now);
+ delay_us = timespec64_to_ns(&delta) / 1000;
+ } while (delay_us <= 0);
+
+ usleep_range(delay_us, (delay_us * 3) >> 1);
} while (!kthread_should_stop());
--
2.15.1
--
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