Re: [PATCH v2] iio: accel: adxl372: Add timestamp to FIFO data

[David Lechner]

On 5/16/26 4:19 PM, Md Shofiqul Islam wrote:
> The driver pushes FIFO samples using iio_push_to_buffers() which does
> not attach a hardware timestamp to the data.  Capture a single timestamp
> per IRQ with iio_get_time_ns() and reuse it for both the event push and
> the FIFO sample loop.
> 
> Use IIO_DECLARE_BUFFER_WITH_TS() for fifo_buf to guarantee the required
> s64 alignment, and switch the FIFO push loop to
> iio_push_to_buffers_with_ts() which accepts an explicit data size and
> timestamp without requiring a separate scan struct or memcpy.
> 
> Add IIO_CHAN_SOFT_TIMESTAMP(3) to the channel spec so the IIO core
> enables scan_timestamp and includes the timestamp slot in the buffer.
> 
> Signed-off-by: Md Shofiqul Islam <shofiqtest@xxxxxxxxx>
> ---
> Changes in v2:
>   - Use IIO_DECLARE_BUFFER_WITH_TS() + iio_push_to_buffers_with_ts() instead
>     of a separate scan struct + memcpy, per review from David Lechner
>   - Add IIO_CHAN_SOFT_TIMESTAMP(3) to channel spec (missing in v1)
>  drivers/iio/accel/adxl372.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/accel/adxl372.c b/drivers/iio/accel/adxl372.c
> index e375d068a..266e80e27 100644
> --- a/drivers/iio/accel/adxl372.c
> +++ b/drivers/iio/accel/adxl372.c
> @@ -344,6 +344,7 @@ static const struct iio_chan_spec adxl372_channels[] = {
>  	ADXL372_ACCEL_CHANNEL(0, ADXL372_X_DATA_H, X),
>  	ADXL372_ACCEL_CHANNEL(1, ADXL372_Y_DATA_H, Y),
>  	ADXL372_ACCEL_CHANNEL(2, ADXL372_Z_DATA_H, Z),
> +	IIO_CHAN_SOFT_TIMESTAMP(3),
>  };
>  
>  struct adxl372_state {
> @@ -365,7 +366,7 @@ struct adxl372_state {
>  	u8				fifo_set_size;
>  	unsigned long			int1_bitmask;
>  	u16				watermark;
> -	__be16				fifo_buf[ADXL372_FIFO_SIZE];
> +	IIO_DECLARE_BUFFER_WITH_TS(__be16, fifo_buf, ADXL372_FIFO_SIZE);
>  	bool				peak_fifo_mode_en;
>  	struct mutex			threshold_m; /* lock for threshold */
>  };
> @@ -703,13 +704,15 @@ static irqreturn_t adxl372_trigger_handler(int irq, void  *p)
>  	struct adxl372_state *st = iio_priv(indio_dev);
>  	u8 status1, status2;
>  	u16 fifo_entries;
> +	s64 ts;
>  	int i, ret;
>  
>  	ret = adxl372_get_status(st, &status1, &status2, &fifo_entries);
>  	if (ret < 0)
>  		goto err;
>  
> -	adxl372_push_event(indio_dev, iio_get_time_ns(indio_dev), status2);
> +	ts = iio_get_time_ns(indio_dev);
> +	adxl372_push_event(indio_dev, ts, status2);
>  
>  	if (st->fifo_mode != ADXL372_FIFO_BYPASSED &&
>  	    ADXL372_STATUS_1_FIFO_FULL(status1)) {
> @@ -733,7 +736,9 @@ static irqreturn_t adxl372_trigger_handler(int irq, void  *p)
>  			/* filter peak detection data */
>  			if (st->peak_fifo_mode_en)
>  				adxl372_arrange_axis_data(st, &st->fifo_buf[i]);
> -			iio_push_to_buffers(indio_dev, &st->fifo_buf[i]);
> +			iio_push_to_buffers_with_ts(indio_dev, &st->fifo_buf[i],
> +						    st->fifo_set_size * sizeof(__be16),

Should just be sizeof(st->fifo_buf), otherwise it doesn't
actually protect against buffer overflow.

> +						    ts);
>  		}
>  	}
>  err: