Re: [PATCH 2/2] iio: hid-sensor-rotation: Fix stale or zero output when reading raw values

[Jonathan Cameron]

On Wed, 10 Jun 2026 16:29:10 +0800
Zhang Lixu <lixu.zhang@xxxxxxxxx> wrote:

> When reading the raw quaternion attribute (in_rot_quaternion_raw), the
> driver currently returns either all zeros (if the sensor was never enabled)
> or stale data (if the sensor was previously enabled) because it reads from
> the internal buffer without explicitly requesting a new sample from the
> sensor.
> 
> To fix this, power up the sensor, call sensor_hub_input_attr_read_values()
> to issue a synchronous GET_REPORT and receive the full quaternion data
> directly into a local buffer, then decode the four components.
> 
> Signed-off-by: Zhang Lixu <lixu.zhang@xxxxxxxxx>
Hi Zhang,

Given this is clearly a fix, can you reply to this thread with an appropriate
Fixes tag.  Otherwise looks fine to me.

Given timing and I guess that this bug is fairly old, this will probably only
go upstream after rc1.

Thanks,

Jonathan

> ---
>  drivers/iio/orientation/hid-sensor-rotation.c | 40 ++++++++++++++++++-
>  1 file changed, 38 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/orientation/hid-sensor-rotation.c b/drivers/iio/orientation/hid-sensor-rotation.c
> index 4a11e45550991..1c6f02374f3ce 100644
> --- a/drivers/iio/orientation/hid-sensor-rotation.c
> +++ b/drivers/iio/orientation/hid-sensor-rotation.c
> @@ -86,6 +86,13 @@ static int dev_rot_read_raw(struct iio_dev *indio_dev,
>  				long mask)
>  {
>  	struct dev_rot_state *rot_state = iio_priv(indio_dev);
> +	struct hid_sensor_hub_device *hsdev = rot_state->common_attributes.hsdev;
> +	struct hid_sensor_hub_attribute_info *info = &rot_state->quaternion;
> +	u32 usage_id = HID_USAGE_SENSOR_ORIENT_QUATERNION;
> +	union {
> +		s16 val16[4];
> +		s32 val32[4];
> +	} raw_buf;
>  	int ret_type;
>  	int i;
>  
> @@ -95,8 +102,37 @@ static int dev_rot_read_raw(struct iio_dev *indio_dev,
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
>  		if (size >= 4) {
> -			for (i = 0; i < 4; ++i)
> -				vals[i] = rot_state->scan.sampled_vals[i];
> +			if (info->size <= 0 || info->size > sizeof(raw_buf))
> +				return -EINVAL;
> +
> +			hid_sensor_power_state(&rot_state->common_attributes, true);
> +
> +			ret_type = sensor_hub_input_attr_read_values(hsdev,
> +								     hsdev->usage,
> +								     usage_id,
> +								     info->report_id,
> +								     SENSOR_HUB_SYNC,
> +								     info->size,
> +								     (u8 *)&raw_buf);
> +
> +			hid_sensor_power_state(&rot_state->common_attributes, false);
> +
> +			if (ret_type < 0)
> +				return ret_type;
> +
> +			switch (info->size) {
> +			case sizeof(raw_buf.val16):
> +				for (i = 0; i < ARRAY_SIZE(raw_buf.val16); i++)
> +					vals[i] = raw_buf.val16[i];
> +				break;
> +			case sizeof(raw_buf.val32):
> +				for (i = 0; i < ARRAY_SIZE(raw_buf.val32); i++)
> +					vals[i] = raw_buf.val32[i];
> +				break;
> +			default:
> +				return -EINVAL;
> +			}
> +
>  			ret_type = IIO_VAL_INT_MULTIPLE;
>  			*val_len =  4;
>  		} else