Re: [PATCH 8/9] iio: imu: st_lsm6dsx: add event configurability on a per axis basis

[Andy Shevchenko]

On Thu, Oct 30, 2025 at 08:27:51AM +0100, Francesco Lavra wrote:
> In order to be able to configure event detection on a per axis
> basis (for either setting an event threshold/sensitivity value, or
> enabling/disabling event detection), add new axis-specific fields
> to struct st_lsm6dsx_event_src, and modify the logic that handles
> event configuration to properly handle axis-specific settings when
> supported by a given event source.
> A future commit will add actual event sources with per-axis
> configurability.

...

> +	old_enable = hw->enable_event[event];
> +	new_enable = state ? (old_enable | BIT(axis)) : (old_enable & ~BIT(axis));
> +	if (!!old_enable == !!new_enable)

This is an interesting check. So, old_enable and new_enable are _not_ booleans, right?
So, this means the check test if _any_ of the bit was set and kept set or none were set
and non is going to be set. Correct? I think a short comment would be good to have.

> +		return 0;

...

> +static const struct st_lsm6dsx_reg *st_lsm6dsx_get_event_reg(struct st_lsm6dsx_hw *hw,
> +							     enum st_lsm6dsx_event_id event,
> +							     const struct iio_chan_spec *chan)
> +{
> +	const struct st_lsm6dsx_event_src *src = &hw->settings->event_settings.sources[event];
> +	const struct st_lsm6dsx_reg *reg;
> +
> +	switch (chan->channel2) {
> +	case IIO_MOD_X:
> +		reg = &src->x_value;
> +		break;
> +	case IIO_MOD_Y:
> +		reg = &src->y_value;
> +		break;
> +	case IIO_MOD_Z:
> +		reg = &src->z_value;
> +		break;
> +	default:
> +		return NULL;
> +	}

> +	if (!reg->addr)
> +		reg = &src->value;
> +	return reg;

	if (reg->addr)
		return reg;

	/* Perhaps a comment here to explain the choice */
	return &src->value;

> +}

-- 
With Best Regards,
Andy Shevchenko