Re: [PATCH v2] iio: imu: inv_mpu6050: stabilized timestamping in interrupt

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 27 May 2024 15:01:17 +0000
inv.git-commit@tdk.com wrote:

> From: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
> 
> Use IRQ ONESHOT flag to ensure the timestamp is not updated in the
> hard handler during the thread handler. And use a fixed value of 1
> sample that correspond to this first timestamp.
> 
> This way we can ensure the timestamp is always corresponding to the
> value used by the timestamping mechanism. Otherwise, it is possible
> that between FIFO count read and FIFO processing the timestamp is
> overwritten in the hard handler.
> 
> Fixes: 111e1abd0045 ("iio: imu: inv_mpu6050: use the common inv_sensors timestamp module")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
Applied
> ---
>  drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c    | 4 ++--
>  drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c | 1 +
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
> index 0dc0f22a5582..3d3b27f28c9d 100644
> --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
> @@ -100,8 +100,8 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
>  		goto end_session;
>  	/* Each FIFO data contains all sensors, so same number for FIFO and sensor data */
>  	fifo_period = NSEC_PER_SEC / INV_MPU6050_DIVIDER_TO_FIFO_RATE(st->chip_config.divider);
> -	inv_sensors_timestamp_interrupt(&st->timestamp, nb, pf->timestamp);
> -	inv_sensors_timestamp_apply_odr(&st->timestamp, fifo_period, nb, 0);
> +	inv_sensors_timestamp_interrupt(&st->timestamp, 1, pf->timestamp);
> +	inv_sensors_timestamp_apply_odr(&st->timestamp, fifo_period, 1, 0);
>  
>  	/* clear internal data buffer for avoiding kernel data leak */
>  	memset(data, 0, sizeof(data));
> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
> index 1b603567ccc8..84273660ca2e 100644
> --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c
> @@ -300,6 +300,7 @@ int inv_mpu6050_probe_trigger(struct iio_dev *indio_dev, int irq_type)
>  	if (!st->trig)
>  		return -ENOMEM;
>  
> +	irq_type |= IRQF_ONESHOT;
>  	ret = devm_request_threaded_irq(&indio_dev->dev, st->irq,
>  					&inv_mpu6050_interrupt_timestamp,
>  					&inv_mpu6050_interrupt_handle,