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

[Zhang Lixu <lixu.zhang@intel.com>]

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@intel.com>
---
 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
-- 
2.43.0