6.6-stable review patch. If anyone has any objections, please let me know.
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From: Mario Tesi martepisa@gmail.com
[ Upstream commit 8abbf45fcda028c2c05ba38eb14ede9fa9e7341b ]
The calibrated timestamp is calculated from the nominal value using the formula: ts_gain[ns] ≈ ts_sensitivity - (ts_trim_coeff * val) / 1000.
The values of ts_sensitivity and ts_trim_coeff are not the same for all devices, so it is necessary to differentiate them based on the part name. For the correct values please consult the relevant AN.
Fixes: cb3b6b8e1bc0 ("iio: imu: st_lsm6dsx: add odr calibration feature") Signed-off-by: Mario Tesi mario.tesi@st.com Acked-by: Lorenzo Bianconi lorenzo@kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h | 18 ++++++++++++++++++ drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c | 19 ++++++++----------- 2 files changed, 26 insertions(+), 11 deletions(-)
diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h index c19237717e812..0f347684f6fc9 100644 --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h @@ -190,6 +190,22 @@ struct st_lsm6dsx_fifo_ops { * @fifo_en: Hw timer FIFO enable register info (addr + mask). * @decimator: Hw timer FIFO decimator register info (addr + mask). * @freq_fine: Difference in % of ODR with respect to the typical. + * @ts_sensitivity: Nominal timestamp sensitivity. + * @ts_trim_coeff: Coefficient for calculating the calibrated timestamp gain. + * This coefficient comes into play when linearizing the formula + * used to calculate the calibrated timestamp (please see the + * relevant formula in the AN for the specific IMU). + * For example, in the case of LSM6DSO we have: + * + * 1 / (1 + x) ~= 1 - x (Taylor’s Series) + * ttrim[s] = 1 / (40000 * (1 + 0.0015 * val)) (from AN5192) + * ttrim[ns] ~= 25000 - 37.5 * val + * ttrim[ns] ~= 25000 - (37500 * val) / 1000 + * + * so, replacing ts_sensitivity = 25000 and + * ts_trim_coeff = 37500 + * + * ttrim[ns] ~= ts_sensitivity - (ts_trim_coeff * val) / 1000 */ struct st_lsm6dsx_hw_ts_settings { struct st_lsm6dsx_reg timer_en; @@ -197,6 +213,8 @@ struct st_lsm6dsx_hw_ts_settings { struct st_lsm6dsx_reg fifo_en; struct st_lsm6dsx_reg decimator; u8 freq_fine; + u16 ts_sensitivity; + u16 ts_trim_coeff; };
/** diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c index b6e6b1df8a618..6e42e0c659e0c 100644 --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c @@ -77,8 +77,6 @@
#define ST_LSM6DSX_REG_WHOAMI_ADDR 0x0f
-#define ST_LSM6DSX_TS_SENSITIVITY 25000UL /* 25us */ - static const struct iio_chan_spec st_lsm6dsx_acc_channels[] = { ST_LSM6DSX_CHANNEL_ACC(IIO_ACCEL, 0x28, IIO_MOD_X, 0), ST_LSM6DSX_CHANNEL_ACC(IIO_ACCEL, 0x2a, IIO_MOD_Y, 1), @@ -962,6 +960,8 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = { .mask = GENMASK(7, 6), }, .freq_fine = 0x63, + .ts_sensitivity = 25000, + .ts_trim_coeff = 37500, }, .shub_settings = { .page_mux = { @@ -1175,6 +1175,8 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = { .mask = GENMASK(7, 6), }, .freq_fine = 0x63, + .ts_sensitivity = 25000, + .ts_trim_coeff = 37500, }, .event_settings = { .enable_reg = { @@ -1350,6 +1352,8 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = { .mask = GENMASK(7, 6), }, .freq_fine = 0x4f, + .ts_sensitivity = 21701, + .ts_trim_coeff = 28212, }, .shub_settings = { .page_mux = { @@ -2243,20 +2247,13 @@ static int st_lsm6dsx_init_hw_timer(struct st_lsm6dsx_hw *hw) }
/* calibrate timestamp sensitivity */ - hw->ts_gain = ST_LSM6DSX_TS_SENSITIVITY; + hw->ts_gain = ts_settings->ts_sensitivity; if (ts_settings->freq_fine) { err = regmap_read(hw->regmap, ts_settings->freq_fine, &val); if (err < 0) return err;
- /* - * linearize the AN5192 formula: - * 1 / (1 + x) ~= 1 - x (Taylor’s Series) - * ttrim[s] = 1 / (40000 * (1 + 0.0015 * val)) - * ttrim[ns] ~= 25000 - 37.5 * val - * ttrim[ns] ~= 25000 - (37500 * val) / 1000 - */ - hw->ts_gain -= ((s8)val * 37500) / 1000; + hw->ts_gain -= ((s8)val * ts_settings->ts_trim_coeff) / 1000; }
return 0;