On 06/05/2018 19:00, Jonathan Cameron wrote:
On Mon, 30 Apr 2018 12:14:10 +0200
Jean-Baptiste Maneyrol <jmaneyrol@xxxxxxxxxxxxxx> wrote:
Implement generic skip first samples mechanism and use it to
filter out first sample when gyro is on.
The problem for these chips is that the first sample of the gyro
is out of specs, because gyro is not completely stabilized. To
ensure all data are within sensor specs, we just skip the first
sample when turning gyro on.
Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@xxxxxxxxxxxxxx>
Neat and tidy solution so good.
Is there a similar issue in the read_raw path which seems to just
flick the gyro on then read from it immediately?
I may be missing a delay there which is preventing the data being
bad though.
Jonathan
Hello,
effectively raw reading should be affected. Since it is using direct
sensor register reading, it should requires adding a correct sleep time.
But direct reading like this is really not very reliable (turn chip and
sensor on/off everytime, which is very bad for stability).
Is it possible to send later an additional patch for fixing this issue
and accept this one? The fix for the 2 are completely unrelated since it
doesn't use the same mechanism (FIFO reading vs register reading).
Thanks.
JB
---
drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h | 1 +
drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c | 7 ++++++-
drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c | 3 +++
3 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
index 142a835..dfb9e4e 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
@@ -148,6 +148,7 @@ struct inv_mpu6050_state {
struct regmap *map;
int irq;
u8 irq_mask;
+ unsigned skip_samples;
};
/*register and associated bit definition*/
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
index e51404f..1b57354 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
@@ -185,7 +185,12 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
if (result == 0)
timestamp = 0;
- iio_push_to_buffers_with_timestamp(indio_dev, data, timestamp);
+ /* skip first samples if needed */
+ if (st->skip_samples)
+ st->skip_samples--;
+ else
+ iio_push_to_buffers_with_timestamp(indio_dev, data,
+ timestamp);
fifo_count -= bytes_per_datum;
}
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
index 8a9f869..0d7db27 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
@@ -49,11 +49,14 @@ static int inv_mpu6050_set_enable(struct iio_dev *indio_dev, bool enable)
if (result)
return result;
inv_scan_query(indio_dev);
+ st->skip_samples = 0;
if (st->chip_config.gyro_fifo_enable) {
result = inv_mpu6050_switch_engine(st, true,
INV_MPU6050_BIT_PWR_GYRO_STBY);
if (result)
goto error_power_off;
+ /* gyro first sample is out of specs, skip it */
+ st->skip_samples = 1;
}
if (st->chip_config.accl_fifo_enable) {
result = inv_mpu6050_switch_engine(st, true,
--
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