Some IMU chips in the LSM6DSX family have sensor fusion features that
combine data from the accelerometer and gyroscope. One of these features
generates rotation vector data and makes it available in the hardware
FIFO as a quaternion (more specifically, the X, Y and Z components of the
quaternion vector, expressed as 16-bit half-precision floating-point
numbers).

Add support for a new sensor instance that allows receiving sensor fusion
data, by defining a new struct st_lsm6dsx_fusion_settings (which contains
chip-specific details for the sensor fusion functionality), and adding this
struct as a new field in struct st_lsm6dsx_settings. In st_lsm6dsx_core.c,
populate this new struct for the LSM6DSV and LSM6DSV16X chips, and add the
logic to initialize an additional IIO device if this struct is populated
for the hardware type being probed.
Note: a new IIO device is being defined (as opposed to adding channels to
an existing device) because the rate at which sensor fusion data is
generated may not match the data rate from any of the existing devices.

Tested on LSM6DSV16X.

Signed-off-by: Francesco Lavra <flavra@baylibre.com>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/iio/imu/st_lsm6dsx/Makefile           |   2 +-
 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h       |  28 +-
 .../iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c    |   9 +-
 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c  |  58 +++++
 .../iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c    | 243 ++++++++++++++++++
 5 files changed, 333 insertions(+), 7 deletions(-)
 create mode 100644 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c

diff --git a/drivers/iio/imu/st_lsm6dsx/Makefile b/drivers/iio/imu/st_lsm6dsx/Makefile
index 57cbcd67d64f..19a488254de3 100644
--- a/drivers/iio/imu/st_lsm6dsx/Makefile
+++ b/drivers/iio/imu/st_lsm6dsx/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 st_lsm6dsx-y := st_lsm6dsx_core.o st_lsm6dsx_buffer.o \
-		st_lsm6dsx_shub.o
+		st_lsm6dsx_shub.o st_lsm6dsx_fusion.o
 
 obj-$(CONFIG_IIO_ST_LSM6DSX) += st_lsm6dsx.o
 obj-$(CONFIG_IIO_ST_LSM6DSX_I2C) += st_lsm6dsx_i2c.o
diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
index 07b1773c87bd..767aadfe7061 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
@@ -294,6 +294,7 @@ enum st_lsm6dsx_sensor_id {
 	ST_LSM6DSX_ID_EXT0,
 	ST_LSM6DSX_ID_EXT1,
 	ST_LSM6DSX_ID_EXT2,
+	ST_LSM6DSX_ID_FUSION,
 	ST_LSM6DSX_ID_MAX
 };
 
@@ -301,6 +302,17 @@ enum st_lsm6dsx_ext_sensor_id {
 	ST_LSM6DSX_ID_MAGN,
 };
 
+struct st_lsm6dsx_fusion_settings {
+	const struct iio_chan_spec *chan;
+	int chan_len;
+	struct st_lsm6dsx_reg odr_reg;
+	int odr_hz[ST_LSM6DSX_ODR_LIST_SIZE];
+	int odr_len;
+	struct st_lsm6dsx_reg fifo_enable;
+	struct st_lsm6dsx_reg page_mux;
+	struct st_lsm6dsx_reg enable;
+};
+
 /**
  * struct st_lsm6dsx_ext_dev_settings - i2c controller slave settings
  * @i2c_addr: I2c slave address list.
@@ -388,6 +400,7 @@ struct st_lsm6dsx_settings {
 	struct st_lsm6dsx_hw_ts_settings ts_settings;
 	struct st_lsm6dsx_shub_settings shub_settings;
 	struct st_lsm6dsx_event_settings event_settings;
+	struct st_lsm6dsx_fusion_settings fusion_settings;
 };
 
 enum st_lsm6dsx_fifo_mode {
@@ -510,6 +523,9 @@ int st_lsm6dsx_check_odr(struct st_lsm6dsx_sensor *sensor, u32 odr, u8 *val);
 int st_lsm6dsx_shub_probe(struct st_lsm6dsx_hw *hw, const char *name);
 int st_lsm6dsx_shub_set_enable(struct st_lsm6dsx_sensor *sensor, bool enable);
 int st_lsm6dsx_shub_read_output(struct st_lsm6dsx_hw *hw, u8 *data, int len);
+int st_lsm6dsx_fusion_probe(struct st_lsm6dsx_hw *hw, const char *name);
+int st_lsm6dsx_fusion_set_enable(struct st_lsm6dsx_sensor *sensor, bool enable);
+int st_lsm6dsx_fusion_set_odr(struct st_lsm6dsx_sensor *sensor, bool enable);
 int st_lsm6dsx_set_page(struct st_lsm6dsx_hw *hw, bool enable);
 
 static inline int
@@ -564,12 +580,14 @@ st_lsm6dsx_get_mount_matrix(const struct iio_dev *iio_dev,
 static inline int
 st_lsm6dsx_device_set_enable(struct st_lsm6dsx_sensor *sensor, bool enable)
 {
-	if (sensor->id == ST_LSM6DSX_ID_EXT0 ||
-	    sensor->id == ST_LSM6DSX_ID_EXT1 ||
-	    sensor->id == ST_LSM6DSX_ID_EXT2)
+	switch (sensor->id) {
+	case ST_LSM6DSX_ID_EXT0 ... ST_LSM6DSX_ID_EXT2:
 		return st_lsm6dsx_shub_set_enable(sensor, enable);
-
-	return st_lsm6dsx_sensor_set_enable(sensor, enable);
+	case ST_LSM6DSX_ID_FUSION:
+		return st_lsm6dsx_fusion_set_enable(sensor, enable);
+	default:
+		return st_lsm6dsx_sensor_set_enable(sensor, enable);
+	}
 }
 
 static const
diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
index 19232146bd61..d5935106a373 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
@@ -88,6 +88,7 @@ enum st_lsm6dsx_fifo_tag {
 	ST_LSM6DSX_EXT0_TAG = 0x0f,
 	ST_LSM6DSX_EXT1_TAG = 0x10,
 	ST_LSM6DSX_EXT2_TAG = 0x11,
+	ST_LSM6DSX_ROT_TAG = 0x13,
 };
 
 static const
@@ -226,8 +227,11 @@ static int st_lsm6dsx_set_fifo_odr(struct st_lsm6dsx_sensor *sensor,
 	u8 data;
 
 	/* Only internal sensors have a FIFO ODR configuration register. */
-	if (sensor->id >= ARRAY_SIZE(hw->settings->batch))
+	if (sensor->id >= ARRAY_SIZE(hw->settings->batch)) {
+		if (sensor->id == ST_LSM6DSX_ID_FUSION)
+			return st_lsm6dsx_fusion_set_odr(sensor, enable);
 		return 0;
+	}
 
 	batch_reg = &hw->settings->batch[sensor->id];
 	if (batch_reg->addr) {
@@ -586,6 +590,9 @@ st_lsm6dsx_push_tagged_data(struct st_lsm6dsx_hw *hw, u8 tag,
 	case ST_LSM6DSX_EXT2_TAG:
 		iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT2];
 		break;
+	case ST_LSM6DSX_ROT_TAG:
+		iio_dev = hw->iio_devs[ST_LSM6DSX_ID_FUSION];
+		break;
 	default:
 		return -EINVAL;
 	}
diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
index 450cb5b47346..630e2cae6f19 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
@@ -94,6 +94,26 @@
 
 #define ST_LSM6DSX_REG_WHOAMI_ADDR		0x0f
 
+/* Raw values from the IMU are 16-bit half-precision floating-point numbers. */
+#define ST_LSM6DSX_CHANNEL_ROT						\
+{									\
+	.type = IIO_ROT,						\
+	.modified = 1,							\
+	.channel2 = IIO_MOD_QUATERNION_AXIS,				\
+	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.info_mask_shared_by_all_available =				\
+		BIT(IIO_CHAN_INFO_SAMP_FREQ),				\
+	.scan_index = 0,						\
+	.scan_type = {							\
+		.format = IIO_SCAN_FORMAT_FLOAT,			\
+		.realbits = 16,						\
+		.storagebits = 16,					\
+		.endianness = IIO_LE,					\
+		.repeat = 3,						\
+	},								\
+	.ext_info = st_lsm6dsx_ext_info,				\
+}
+
 static const struct iio_event_spec st_lsm6dsx_ev_motion[] = {
 	{
 		.type = IIO_EV_TYPE_THRESH,
@@ -153,6 +173,11 @@ static const struct iio_chan_spec st_lsm6ds0_gyro_channels[] = {
 	IIO_CHAN_SOFT_TIMESTAMP(3),
 };
 
+static const struct iio_chan_spec st_lsm6dsx_fusion_channels[] = {
+	ST_LSM6DSX_CHANNEL_ROT,
+	IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
 static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = {
 	{
 		.reset = {
@@ -1492,6 +1517,33 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = {
 				},
 			},
 		},
+		.fusion_settings = {
+			.chan = st_lsm6dsx_fusion_channels,
+			.chan_len = ARRAY_SIZE(st_lsm6dsx_fusion_channels),
+			.odr_reg = {
+				.addr = 0x5e,
+				.mask = GENMASK(5, 3),
+			},
+			.odr_hz[0] = 15,
+			.odr_hz[1] = 30,
+			.odr_hz[2] = 60,
+			.odr_hz[3] = 120,
+			.odr_hz[4] = 240,
+			.odr_hz[5] = 480,
+			.odr_len = 6,
+			.fifo_enable = {
+				.addr = 0x44,
+				.mask = BIT(1),
+			},
+			.page_mux = {
+				.addr = 0x01,
+				.mask = BIT(7),
+			},
+			.enable = {
+				.addr = 0x04,
+				.mask = BIT(1),
+			},
+		},
 	},
 	{
 		.reset = {
@@ -2899,6 +2951,12 @@ int st_lsm6dsx_probe(struct device *dev, int irq, int hw_id,
 			return err;
 	}
 
+	if (hw->settings->fusion_settings.chan) {
+		err = st_lsm6dsx_fusion_probe(hw, name);
+		if (err)
+			return err;
+	}
+
 	if (hw->irq > 0) {
 		err = st_lsm6dsx_irq_setup(hw);
 		if (err < 0)
diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c
new file mode 100644
index 000000000000..9fb3e19e4a55
--- /dev/null
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * STMicroelectronics st_lsm6dsx IMU sensor fusion
+ *
+ * Copyright 2026 BayLibre, SAS
+ */
+
+#include <linux/cleanup.h>
+#include <linux/errno.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/sprintf.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include "st_lsm6dsx.h"
+
+static int
+st_lsm6dsx_fusion_get_odr_val(const struct st_lsm6dsx_fusion_settings *settings,
+			      u32 odr_mHz, u8 *val)
+{
+	int odr_hz = odr_mHz / MILLI;
+	int i;
+
+	for (i = 0; i < settings->odr_len; i++) {
+		if (settings->odr_hz[i] == odr_hz)
+			break;
+	}
+	if (i == settings->odr_len)
+		return -EINVAL;
+
+	*val = i;
+	return 0;
+}
+
+/**
+ * st_lsm6dsx_fusion_page_enable - Enable access to sensor fusion configuration
+ * registers.
+ * @hw: Sensor hardware instance.
+ *
+ * Return: 0 on success, negative value on error.
+ */
+static int st_lsm6dsx_fusion_page_enable(struct st_lsm6dsx_hw *hw)
+{
+	const struct st_lsm6dsx_reg *mux;
+
+	mux = &hw->settings->fusion_settings.page_mux;
+
+	return regmap_set_bits(hw->regmap, mux->addr, mux->mask);
+}
+
+/**
+ * st_lsm6dsx_fusion_page_disable - Disable access to sensor fusion
+ * configuration registers.
+ * @hw: Sensor hardware instance.
+ *
+ * Return: 0 on success, negative value on error.
+ */
+static int st_lsm6dsx_fusion_page_disable(struct st_lsm6dsx_hw *hw)
+{
+	const struct st_lsm6dsx_reg *mux;
+
+	mux = &hw->settings->fusion_settings.page_mux;
+
+	return regmap_clear_bits(hw->regmap, mux->addr, mux->mask);
+}
+
+static int st_lsm6dsx_fusion_set_odr_locked(struct st_lsm6dsx_sensor *sensor,
+					    bool enable)
+{
+	const struct st_lsm6dsx_fusion_settings *settings;
+	struct st_lsm6dsx_hw *hw = sensor->hw;
+	int err;
+
+	settings = &hw->settings->fusion_settings;
+	if (enable) {
+		const struct st_lsm6dsx_reg *reg = &settings->odr_reg;
+		u8 odr_val;
+		u8 data;
+
+		st_lsm6dsx_fusion_get_odr_val(settings, sensor->hwfifo_odr_mHz,
+					      &odr_val);
+		data = ST_LSM6DSX_SHIFT_VAL(odr_val, reg->mask);
+		err = regmap_update_bits(hw->regmap, reg->addr, reg->mask,
+					 data);
+		if (err)
+			return err;
+	}
+
+	return regmap_assign_bits(hw->regmap, settings->fifo_enable.addr,
+				  settings->fifo_enable.mask, enable);
+}
+
+int st_lsm6dsx_fusion_set_enable(struct st_lsm6dsx_sensor *sensor, bool enable)
+{
+	struct st_lsm6dsx_hw *hw = sensor->hw;
+	const struct st_lsm6dsx_reg *en_reg;
+	int err;
+
+	guard(mutex)(&hw->page_lock);
+
+	en_reg = &hw->settings->fusion_settings.enable;
+	err = st_lsm6dsx_fusion_page_enable(hw);
+	if (err)
+		return err;
+
+	err = regmap_assign_bits(hw->regmap, en_reg->addr, en_reg->mask, enable);
+	if (err) {
+		st_lsm6dsx_fusion_page_disable(hw);
+		return err;
+	}
+
+	return st_lsm6dsx_fusion_page_disable(hw);
+}
+
+int st_lsm6dsx_fusion_set_odr(struct st_lsm6dsx_sensor *sensor, bool enable)
+{
+	struct st_lsm6dsx_hw *hw = sensor->hw;
+	int err;
+
+	guard(mutex)(&hw->page_lock);
+
+	err = st_lsm6dsx_fusion_page_enable(hw);
+	if (err)
+		return err;
+
+	err = st_lsm6dsx_fusion_set_odr_locked(sensor, enable);
+	if (err) {
+		st_lsm6dsx_fusion_page_disable(hw);
+		return err;
+	}
+
+	return st_lsm6dsx_fusion_page_disable(hw);
+
+out:
+}
+
+static int st_lsm6dsx_fusion_read_raw(struct iio_dev *iio_dev,
+				      struct iio_chan_spec const *ch,
+				      int *val, int *val2, long mask)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = sensor->hwfifo_odr_mHz / MILLI;
+		*val2 = (sensor->hwfifo_odr_mHz % MILLI) * (MICRO / MILLI);
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int st_lsm6dsx_fusion_write_raw(struct iio_dev *iio_dev,
+				       struct iio_chan_spec const *chan,
+				       int val, int val2, long mask)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
+	const struct st_lsm6dsx_fusion_settings *settings;
+	int err;
+
+	settings = &sensor->hw->settings->fusion_settings;
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ: {
+		u32 odr_mHz = val * MILLI + val2 * (MILLI / MICRO);
+		u8 odr_val;
+
+		/* check that the requested frequency is supported */
+		err = st_lsm6dsx_fusion_get_odr_val(settings, odr_mHz, &odr_val);
+		if (err)
+			return err;
+
+		sensor->hwfifo_odr_mHz = odr_mHz;
+		return 0;
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int st_lsm6dsx_fusion_read_avail(struct iio_dev *indio_dev,
+					struct iio_chan_spec const *chan,
+					const int **vals, int *type,
+					int *length, long mask)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(indio_dev);
+	const struct st_lsm6dsx_fusion_settings *settings;
+
+	settings = &sensor->hw->settings->fusion_settings;
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*vals = settings->odr_hz;
+		*type = IIO_VAL_INT;
+		*length = settings->odr_len;
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info st_lsm6dsx_fusion_info = {
+	.read_raw = st_lsm6dsx_fusion_read_raw,
+	.read_avail = st_lsm6dsx_fusion_read_avail,
+	.write_raw = st_lsm6dsx_fusion_write_raw,
+	.hwfifo_set_watermark = st_lsm6dsx_set_watermark,
+};
+
+int st_lsm6dsx_fusion_probe(struct st_lsm6dsx_hw *hw, const char *name)
+{
+	const struct st_lsm6dsx_fusion_settings *settings;
+	struct st_lsm6dsx_sensor *sensor;
+	struct iio_dev *iio_dev;
+	int ret;
+
+	iio_dev = devm_iio_device_alloc(hw->dev, sizeof(*sensor));
+	if (!iio_dev)
+		return -ENOMEM;
+
+	settings = &hw->settings->fusion_settings;
+	sensor = iio_priv(iio_dev);
+	sensor->id = ST_LSM6DSX_ID_FUSION;
+	sensor->hw = hw;
+	sensor->hwfifo_odr_mHz = settings->odr_hz[0] * MILLI;
+	sensor->watermark = 1;
+	iio_dev->modes = INDIO_DIRECT_MODE;
+	iio_dev->info = &st_lsm6dsx_fusion_info;
+	iio_dev->channels = settings->chan;
+	iio_dev->num_channels = settings->chan_len;
+	ret = snprintf(sensor->name, sizeof(sensor->name), "%s_fusion", name);
+	if (ret >= sizeof(sensor->name))
+		return -E2BIG;
+	iio_dev->name = sensor->name;
+
+	/*
+	 * Put the IIO device pointer in the iio_devs array so that the caller
+	 * can set up a buffer and register this IIO device.
+	 */
+	hw->iio_devs[ST_LSM6DSX_ID_FUSION] = iio_dev;
+
+	return 0;
+}
-- 
2.39.5

Hi Francesco,

kernel test robot noticed the following build warnings:

[auto build test WARNING on next-20260323]
[cannot apply to jic23-iio/togreg linus/master v7.0-rc5 v7.0-rc4 v7.0-rc3 v7.0-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Francesco-Lavra/iio-imu-st_lsm6dsx-Fix-check-for-invalid-samples-from-FIFO/20260325-021519
base:   next-20260323
patch link:    https://lore.kernel.org/r/20260324084808.654118-1-flavra%40baylibre.com
patch subject: [PATCH v9 6/6] iio: imu: st_lsm6dsx: Add support for rotation sensor
config: hexagon-allmodconfig (https://download.01.org/0day-ci/archive/20260326/202603260526.WbXSysM8-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260326/202603260526.WbXSysM8-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603260526.WbXSysM8-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c:138:1: warning: label at end of compound statement is a C2x extension [-Wc2x-extensions]
     138 | }
         | ^
   drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c:137:1: warning: unused label 'out' [-Wunused-label]
     137 | out:
         | ^~~~
   2 warnings generated.


vim +138 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c

   117	
   118	int st_lsm6dsx_fusion_set_odr(struct st_lsm6dsx_sensor *sensor, bool enable)
   119	{
   120		struct st_lsm6dsx_hw *hw = sensor->hw;
   121		int err;
   122	
   123		guard(mutex)(&hw->page_lock);
   124	
   125		err = st_lsm6dsx_fusion_page_enable(hw);
   126		if (err)
   127			return err;
   128	
   129		err = st_lsm6dsx_fusion_set_odr_locked(sensor, enable);
   130		if (err) {
   131			st_lsm6dsx_fusion_page_disable(hw);
   132			return err;
   133		}
   134	
   135		return st_lsm6dsx_fusion_page_disable(hw);
   136	
   137	out:
 > 138	}
   139	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Hi Francesco,

kernel test robot noticed the following build warnings:

[auto build test WARNING on next-20260323]
[cannot apply to jic23-iio/togreg linus/master v7.0-rc5 v7.0-rc4 v7.0-rc3 v7.0-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Francesco-Lavra/iio-imu-st_lsm6dsx-Fix-check-for-invalid-samples-from-FIFO/20260325-021519
base:   next-20260323
patch link:    https://lore.kernel.org/r/20260324084808.654118-1-flavra%40baylibre.com
patch subject: [PATCH v9 6/6] iio: imu: st_lsm6dsx: Add support for rotation sensor
config: arm-randconfig-001-20260326 (https://download.01.org/0day-ci/archive/20260326/202603260457.MZI9sXnu-lkp@intel.com/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project 054e11d1a17e5ba88bb1a8ef32fad3346e80b186)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260326/202603260457.MZI9sXnu-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603260457.MZI9sXnu-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c:138:1: warning: label at end of compound statement is a C23 extension [-Wc23-extensions]
     138 | }
         | ^
>> drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c:137:1: warning: unused label 'out' [-Wunused-label]
     137 | out:
         | ^~~~
   2 warnings generated.


vim +138 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c

   117	
   118	int st_lsm6dsx_fusion_set_odr(struct st_lsm6dsx_sensor *sensor, bool enable)
   119	{
   120		struct st_lsm6dsx_hw *hw = sensor->hw;
   121		int err;
   122	
   123		guard(mutex)(&hw->page_lock);
   124	
   125		err = st_lsm6dsx_fusion_page_enable(hw);
   126		if (err)
   127			return err;
   128	
   129		err = st_lsm6dsx_fusion_set_odr_locked(sensor, enable);
   130		if (err) {
   131			st_lsm6dsx_fusion_page_disable(hw);
   132			return err;
   133		}
   134	
   135		return st_lsm6dsx_fusion_page_disable(hw);
   136	
 > 137	out:
 > 138	}
   139	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Hi Francesco,

kernel test robot noticed the following build errors:

[auto build test ERROR on next-20260323]
[cannot apply to jic23-iio/togreg linus/master v7.0-rc5 v7.0-rc4 v7.0-rc3 v7.0-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Francesco-Lavra/iio-imu-st_lsm6dsx-Fix-check-for-invalid-samples-from-FIFO/20260325-021519
base:   next-20260323
patch link:    https://lore.kernel.org/r/20260324084808.654118-1-flavra%40baylibre.com
patch subject: [PATCH v9 6/6] iio: imu: st_lsm6dsx: Add support for rotation sensor
config: parisc-randconfig-r072-20260326 (https://download.01.org/0day-ci/archive/20260326/202603260349.g0aoRPw8-lkp@intel.com/config)
compiler: hppa-linux-gcc (GCC) 8.5.0
smatch: v0.5.0-9004-gb810ac53
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260326/202603260349.g0aoRPw8-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603260349.g0aoRPw8-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

   drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c: In function 'st_lsm6dsx_fusion_set_odr':
>> drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c:137:1: error: label at end of compound statement
    out:
    ^~~
>> drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c:137:1: warning: label 'out' defined but not used [-Wunused-label]


vim +137 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c

   117	
   118	int st_lsm6dsx_fusion_set_odr(struct st_lsm6dsx_sensor *sensor, bool enable)
   119	{
   120		struct st_lsm6dsx_hw *hw = sensor->hw;
   121		int err;
   122	
   123		guard(mutex)(&hw->page_lock);
   124	
   125		err = st_lsm6dsx_fusion_page_enable(hw);
   126		if (err)
   127			return err;
   128	
   129		err = st_lsm6dsx_fusion_set_odr_locked(sensor, enable);
   130		if (err) {
   131			st_lsm6dsx_fusion_page_disable(hw);
   132			return err;
   133		}
   134	
   135		return st_lsm6dsx_fusion_page_disable(hw);
   136	
 > 137	out:
   138	}
   139	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

On Tue, 24 Mar 2026 09:48:07 +0100
Francesco Lavra <flavra@baylibre.com> wrote:

> Some IMU chips in the LSM6DSX family have sensor fusion features that
> combine data from the accelerometer and gyroscope. One of these features
> generates rotation vector data and makes it available in the hardware
> FIFO as a quaternion (more specifically, the X, Y and Z components of the
> quaternion vector, expressed as 16-bit half-precision floating-point
> numbers).
> 
> Add support for a new sensor instance that allows receiving sensor fusion
> data, by defining a new struct st_lsm6dsx_fusion_settings (which contains
> chip-specific details for the sensor fusion functionality), and adding this
> struct as a new field in struct st_lsm6dsx_settings. In st_lsm6dsx_core.c,
> populate this new struct for the LSM6DSV and LSM6DSV16X chips, and add the
> logic to initialize an additional IIO device if this struct is populated
> for the hardware type being probed.
> Note: a new IIO device is being defined (as opposed to adding channels to
> an existing device) because the rate at which sensor fusion data is
> generated may not match the data rate from any of the existing devices.
> 
> Tested on LSM6DSV16X.
> 
> Signed-off-by: Francesco Lavra <flavra@baylibre.com>
> Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
One trivial thing. But don't resend for that. Assuming nothing else comes
up I'll tweak it whilst applying.  Same for Andy's line wrap comment.

thanks,

Jonathan

> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c
> new file mode 100644
> index 000000000000..9fb3e19e4a55
> --- /dev/null
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c
> @@ -0,0 +1,243 @@

> +
> +int st_lsm6dsx_fusion_set_odr(struct st_lsm6dsx_sensor *sensor, bool enable)
> +{
> +	struct st_lsm6dsx_hw *hw = sensor->hw;
> +	int err;
> +
> +	guard(mutex)(&hw->page_lock);
> +
> +	err = st_lsm6dsx_fusion_page_enable(hw);
> +	if (err)
> +		return err;
> +
> +	err = st_lsm6dsx_fusion_set_odr_locked(sensor, enable);
> +	if (err) {
> +		st_lsm6dsx_fusion_page_disable(hw);
> +		return err;
> +	}
> +
> +	return st_lsm6dsx_fusion_page_disable(hw);
> +
> +out:
Stray.  If nothing else comes up I'll drop this whilst applying.

> +}

On Wed, 25 Mar 2026 14:55:26 +0000
Jonathan Cameron <jonathan.cameron@huawei.com> wrote:

> On Tue, 24 Mar 2026 09:48:07 +0100
> Francesco Lavra <flavra@baylibre.com> wrote:
> 
> > Some IMU chips in the LSM6DSX family have sensor fusion features that
> > combine data from the accelerometer and gyroscope. One of these features
> > generates rotation vector data and makes it available in the hardware
> > FIFO as a quaternion (more specifically, the X, Y and Z components of the
> > quaternion vector, expressed as 16-bit half-precision floating-point
> > numbers).
> > 
> > Add support for a new sensor instance that allows receiving sensor fusion
> > data, by defining a new struct st_lsm6dsx_fusion_settings (which contains
> > chip-specific details for the sensor fusion functionality), and adding this
> > struct as a new field in struct st_lsm6dsx_settings. In st_lsm6dsx_core.c,
> > populate this new struct for the LSM6DSV and LSM6DSV16X chips, and add the
> > logic to initialize an additional IIO device if this struct is populated
> > for the hardware type being probed.
> > Note: a new IIO device is being defined (as opposed to adding channels to
> > an existing device) because the rate at which sensor fusion data is
> > generated may not match the data rate from any of the existing devices.
> > 
> > Tested on LSM6DSV16X.
> > 
> > Signed-off-by: Francesco Lavra <flavra@baylibre.com>
> > Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>  
> One trivial thing. But don't resend for that. Assuming nothing else comes
> up I'll tweak it whilst applying.  Same for Andy's line wrap comment.
> 

Ah. I tried to pick up the series but we have a dependency on a fix
that hasn't quite made it upstream yet and I don't want the complexity
of merging my own fixes branch in until I know that made it upstream.

Sorry, I don't think I can get this merged this cycle unless we go
to rc8. Will get it queued from start of next cycle.

Jonathan

> thanks,
> 
> Jonathan
> 
> > diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c
> > new file mode 100644
> > index 000000000000..9fb3e19e4a55
> > --- /dev/null
> > +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_fusion.c
> > @@ -0,0 +1,243 @@  
> 
> > +
> > +int st_lsm6dsx_fusion_set_odr(struct st_lsm6dsx_sensor *sensor, bool enable)
> > +{
> > +	struct st_lsm6dsx_hw *hw = sensor->hw;
> > +	int err;
> > +
> > +	guard(mutex)(&hw->page_lock);
> > +
> > +	err = st_lsm6dsx_fusion_page_enable(hw);
> > +	if (err)
> > +		return err;
> > +
> > +	err = st_lsm6dsx_fusion_set_odr_locked(sensor, enable);
> > +	if (err) {
> > +		st_lsm6dsx_fusion_page_disable(hw);
> > +		return err;
> > +	}
> > +
> > +	return st_lsm6dsx_fusion_page_disable(hw);
> > +
> > +out:  
> Stray.  If nothing else comes up I'll drop this whilst applying.
> 
> > +}