Re: [PATCH 1/2] iio: imu: st_lsm6dsx: fix read misalignment on untagged FIFO

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 13 Mar 2020 18:54:41 +0100
Lorenzo Bianconi <lorenzo@kernel.org> wrote:

> st_lsm6dsx suffers of a read misalignment on untagged FIFO when
> all 3 supported sensors (accel, gyro and ext device) are running
> at different ODRs (the use-case is reported in the LSM6DSM Application
> Note at pag 100).
> Fix the issue taking into account decimation factor reading the FIFO
> pattern.
> 
> Fixes: e485e2a2cfd6 ("iio: imu: st_lsm6dsx: enable sensor-hub support for lsm6dsm")
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Queued up.  Not totally sure which branch this will through, but may
well be in next merge window because of timing.

Thanks,

Jonathan

> ---
>  drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h       |  2 ++
>  .../iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c    | 23 +++++++++++++------
>  2 files changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> index f2113a63721a..e9e756b1e92f 100644
> --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> @@ -337,6 +337,7 @@ enum st_lsm6dsx_fifo_mode {
>   * @gain: Configured sensor sensitivity.
>   * @odr: Output data rate of the sensor [Hz].
>   * @watermark: Sensor watermark level.
> + * @decimator: Sensor decimation factor.
>   * @sip: Number of samples in a given pattern.
>   * @ts_ref: Sensor timestamp reference for hw one.
>   * @ext_info: Sensor settings if it is connected to i2c controller
> @@ -350,6 +351,7 @@ struct st_lsm6dsx_sensor {
>  	u32 odr;
>  
>  	u16 watermark;
> +	u8 decimator;
>  	u8 sip;
>  	s64 ts_ref;
>  
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> index bb899345f2bb..afd00daeefb2 100644
> --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> @@ -93,6 +93,7 @@ st_lsm6dsx_get_decimator_val(struct st_lsm6dsx_sensor *sensor, u32 max_odr)
>  			break;
>  	}
>  
> +	sensor->decimator = decimator;
>  	return i == max_size ? 0 : st_lsm6dsx_decimator_table[i].val;
>  }
>  
> @@ -337,7 +338,7 @@ static inline int st_lsm6dsx_read_block(struct st_lsm6dsx_hw *hw, u8 addr,
>  int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
>  {
>  	struct st_lsm6dsx_sensor *acc_sensor, *gyro_sensor, *ext_sensor = NULL;
> -	int err, acc_sip, gyro_sip, ts_sip, ext_sip, read_len, offset;
> +	int err, sip, acc_sip, gyro_sip, ts_sip, ext_sip, read_len, offset;
>  	u16 fifo_len, pattern_len = hw->sip * ST_LSM6DSX_SAMPLE_SIZE;
>  	u16 fifo_diff_mask = hw->settings->fifo_ops.fifo_diff.mask;
>  	u8 gyro_buff[ST_LSM6DSX_IIO_BUFF_SIZE];
> @@ -399,19 +400,20 @@ int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
>  		acc_sip = acc_sensor->sip;
>  		ts_sip = hw->ts_sip;
>  		offset = 0;
> +		sip = 0;
>  
>  		while (acc_sip > 0 || gyro_sip > 0 || ext_sip > 0) {
> -			if (gyro_sip > 0) {
> +			if (gyro_sip > 0 && !(sip % gyro_sensor->decimator)) {
>  				memcpy(gyro_buff, &hw->buff[offset],
>  				       ST_LSM6DSX_SAMPLE_SIZE);
>  				offset += ST_LSM6DSX_SAMPLE_SIZE;
>  			}
> -			if (acc_sip > 0) {
> +			if (acc_sip > 0 && !(sip % acc_sensor->decimator)) {
>  				memcpy(acc_buff, &hw->buff[offset],
>  				       ST_LSM6DSX_SAMPLE_SIZE);
>  				offset += ST_LSM6DSX_SAMPLE_SIZE;
>  			}
> -			if (ext_sip > 0) {
> +			if (ext_sip > 0 && !(sip % ext_sensor->decimator)) {
>  				memcpy(ext_buff, &hw->buff[offset],
>  				       ST_LSM6DSX_SAMPLE_SIZE);
>  				offset += ST_LSM6DSX_SAMPLE_SIZE;
> @@ -441,18 +443,25 @@ int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
>  				offset += ST_LSM6DSX_SAMPLE_SIZE;
>  			}
>  
> -			if (gyro_sip-- > 0)
> +			if (gyro_sip > 0 && !(sip % gyro_sensor->decimator)) {
>  				iio_push_to_buffers_with_timestamp(
>  					hw->iio_devs[ST_LSM6DSX_ID_GYRO],
>  					gyro_buff, gyro_sensor->ts_ref + ts);
> -			if (acc_sip-- > 0)
> +				gyro_sip--;
> +			}
> +			if (acc_sip > 0 && !(sip % acc_sensor->decimator)) {
>  				iio_push_to_buffers_with_timestamp(
>  					hw->iio_devs[ST_LSM6DSX_ID_ACC],
>  					acc_buff, acc_sensor->ts_ref + ts);
> -			if (ext_sip-- > 0)
> +				acc_sip--;
> +			}
> +			if (ext_sip > 0 && !(sip % ext_sensor->decimator)) {
>  				iio_push_to_buffers_with_timestamp(
>  					hw->iio_devs[ST_LSM6DSX_ID_EXT0],
>  					ext_buff, ext_sensor->ts_ref + ts);
> +				ext_sip--;
> +			}
> +			sip++;
>  		}
>  	}
>