[PATCH AUTOSEL 6.3 04/24] iio: imu: st_lsm6dsx: discard samples during filters settling time

From: Sasha Levin
Date: Sat May 06 2023 - 20:30:48 EST

From: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>

[ Upstream commit db3c490503bee4d0611f9fc17fcd8cfe6fcdbcad ]

During digital filters settling time the driver is expected to drop
samples since they can be corrupted. Introduce the capability to drop
a given number of samples according to the configured ODR.
Add sample_to_discard for LSM6DSM-like sensors since new generation
devices (e.g. LSM6DSO) support DRDY mask where corrupted samples are
masked in hw with values greather than 0x7ffd so the driver can easily
discard them.
I have not added sample_to_discard support for LSM6DS3 or LSM6DS3H since
I do not have any sample for testing at the moment.

Reported-by: Philippe De Muyter <phdm@xxxxxxxxx>
Tested-by: Philippe De Muyter <phdm@xxxxxxxxx>
Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/21dcd94935c147ef9b1da4984b3da6264ee9609e.1677496295.git.lorenzo@xxxxxxxxxx
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h | 11 ++++
.../iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c | 57 ++++++++++++++++---
drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c | 18 ++++++
3 files changed, 78 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
index 499fcf8875b40..8e119d78730ba 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
@@ -137,6 +137,13 @@ struct st_lsm6dsx_odr_table_entry {
int odr_len;
};

+struct st_lsm6dsx_samples_to_discard {
+ struct {
+ u32 milli_hz;
+ u16 samples;
+ } val[ST_LSM6DSX_ODR_LIST_SIZE];
+};
+
struct st_lsm6dsx_fs {
u32 gain;
u8 val;
@@ -291,6 +298,7 @@ struct st_lsm6dsx_ext_dev_settings {
* @irq_config: interrupts related registers.
* @drdy_mask: register info for data-ready mask (addr + mask).
* @odr_table: Hw sensors odr table (Hz + val).
+ * @samples_to_discard: Number of samples to discard for filters settling time.
* @fs_table: Hw sensors gain table (gain + val).
* @decimator: List of decimator register info (addr + mask).
* @batch: List of FIFO batching register info (addr + mask).
@@ -323,6 +331,7 @@ struct st_lsm6dsx_settings {
} irq_config;
struct st_lsm6dsx_reg drdy_mask;
struct st_lsm6dsx_odr_table_entry odr_table[2];
+ struct st_lsm6dsx_samples_to_discard samples_to_discard[2];
struct st_lsm6dsx_fs_table_entry fs_table[2];
struct st_lsm6dsx_reg decimator[ST_LSM6DSX_MAX_ID];
struct st_lsm6dsx_reg batch[ST_LSM6DSX_MAX_ID];
@@ -353,6 +362,7 @@ enum st_lsm6dsx_fifo_mode {
* @hw: Pointer to instance of struct st_lsm6dsx_hw.
* @gain: Configured sensor sensitivity.
* @odr: Output data rate of the sensor [Hz].
+ * @samples_to_discard: Number of samples to discard for filters settling time.
* @watermark: Sensor watermark level.
* @decimator: Sensor decimation factor.
* @sip: Number of samples in a given pattern.
@@ -367,6 +377,7 @@ struct st_lsm6dsx_sensor {
u32 gain;
u32 odr;

+ u16 samples_to_discard;
u16 watermark;
u8 decimator;
u8 sip;
diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
index 7dd5205aea5b4..f6c11d6fb0b0f 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
@@ -457,17 +457,31 @@ int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
}

if (gyro_sip > 0 && !(sip % gyro_sensor->decimator)) {
- iio_push_to_buffers_with_timestamp(
- hw->iio_devs[ST_LSM6DSX_ID_GYRO],
- &hw->scan[ST_LSM6DSX_ID_GYRO],
- gyro_sensor->ts_ref + ts);
+ /*
+ * We need to discards gyro samples during
+ * filters settling time
+ */
+ if (gyro_sensor->samples_to_discard > 0)
+ gyro_sensor->samples_to_discard--;
+ else
+ iio_push_to_buffers_with_timestamp(
+ hw->iio_devs[ST_LSM6DSX_ID_GYRO],
+ &hw->scan[ST_LSM6DSX_ID_GYRO],
+ gyro_sensor->ts_ref + ts);
gyro_sip--;
}
if (acc_sip > 0 && !(sip % acc_sensor->decimator)) {
- iio_push_to_buffers_with_timestamp(
- hw->iio_devs[ST_LSM6DSX_ID_ACC],
- &hw->scan[ST_LSM6DSX_ID_ACC],
- acc_sensor->ts_ref + ts);
+ /*
+ * We need to discards accel samples during
+ * filters settling time
+ */
+ if (acc_sensor->samples_to_discard > 0)
+ acc_sensor->samples_to_discard--;
+ else
+ iio_push_to_buffers_with_timestamp(
+ hw->iio_devs[ST_LSM6DSX_ID_ACC],
+ &hw->scan[ST_LSM6DSX_ID_ACC],
+ acc_sensor->ts_ref + ts);
acc_sip--;
}
if (ext_sip > 0 && !(sip % ext_sensor->decimator)) {
@@ -654,6 +668,30 @@ int st_lsm6dsx_flush_fifo(struct st_lsm6dsx_hw *hw)
return err;
}

+static void
+st_lsm6dsx_update_samples_to_discard(struct st_lsm6dsx_sensor *sensor)
+{
+ const struct st_lsm6dsx_samples_to_discard *data;
+ struct st_lsm6dsx_hw *hw = sensor->hw;
+ int i;
+
+ if (sensor->id != ST_LSM6DSX_ID_GYRO &&
+ sensor->id != ST_LSM6DSX_ID_ACC)
+ return;
+
+ /* check if drdy mask is supported in hw */
+ if (hw->settings->drdy_mask.addr)
+ return;
+
+ data = &hw->settings->samples_to_discard[sensor->id];
+ for (i = 0; i < ST_LSM6DSX_ODR_LIST_SIZE; i++) {
+ if (data->val[i].milli_hz == sensor->odr) {
+ sensor->samples_to_discard = data->val[i].samples;
+ return;
+ }
+ }
+}
+
int st_lsm6dsx_update_fifo(struct st_lsm6dsx_sensor *sensor, bool enable)
{
struct st_lsm6dsx_hw *hw = sensor->hw;
@@ -673,6 +711,9 @@ int st_lsm6dsx_update_fifo(struct st_lsm6dsx_sensor *sensor, bool enable)
goto out;
}

+ if (enable)
+ st_lsm6dsx_update_samples_to_discard(sensor);
+
err = st_lsm6dsx_device_set_enable(sensor, enable);
if (err < 0)
goto out;
diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
index 3f6060c64f32b..966df6ffe8740 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
@@ -634,6 +634,24 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = {
.fs_len = 4,
},
},
+ .samples_to_discard = {
+ [ST_LSM6DSX_ID_ACC] = {
+ .val[0] = { 12500, 1 },
+ .val[1] = { 26000, 1 },
+ .val[2] = { 52000, 1 },
+ .val[3] = { 104000, 2 },
+ .val[4] = { 208000, 2 },
+ .val[5] = { 416000, 2 },
+ },
+ [ST_LSM6DSX_ID_GYRO] = {
+ .val[0] = { 12500, 2 },
+ .val[1] = { 26000, 5 },
+ .val[2] = { 52000, 7 },
+ .val[3] = { 104000, 12 },
+ .val[4] = { 208000, 20 },
+ .val[5] = { 416000, 36 },
+ },
+ },
.irq_config = {
.irq1 = {
.addr = 0x0d,
--
2.39.2