Re: [PATCH v2 3/3] iio: imu: st_lsm6dsx: Add support for rotation sensor

[Andy Shevchenko]

On Thu, Jan 15, 2026 at 02:32:11PM +0100, Lorenzo Bianconi 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_sf_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 LSMDSV16X.

...

> > +	settings = &sensor->hw->settings->sf_settings;
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_SAMP_FREQ: {
> > +		u32 odr_mHz;
> > +		u8 odr_val;
> > +
> > +		odr_mHz = val * MILLI + val2 * MILLI / MICRO;
> > +		err = st_lsm6dsx_sf_get_odr_val(settings, odr_mHz, &odr_val);
> > +		if (err)
> > +			return err;
> > +
> > +		sensor->hwfifo_odr_mHz = odr_mHz;
> > +		return 0;
> 
> break;
> 
> > +	}
> > +	default:
> > +		return -EINVAL;
> 
> break;
> 
> > +	}
> 
> return err;

Why?

-- 
With Best Regards,
Andy Shevchenko