[PATCH 4/5] HID: playstation: correct DualShock4 gyro bias handling.

[Roderick Colenbrander <roderick@gaikai.com>]

The bias for the gyroscope is not used correctly. The sensor bias
needs to be used in calculation of the 'sensivity' instead of being
an offset.

In practice this has little input on the values as the bias values
tends to be small (+/- 20).

Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com>
---
 drivers/hid/hid-playstation.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/hid/hid-playstation.c b/drivers/hid/hid-playstation.c
index 11bb6caf7412..1001eab6ff75 100644
--- a/drivers/hid/hid-playstation.c
+++ b/drivers/hid/hid-playstation.c
@@ -1848,19 +1848,22 @@ static int dualshock4_get_calibration_data(struct dualshock4 *ds4)
 	 */
 	speed_2x = (gyro_speed_plus + gyro_speed_minus);
 	ds4->gyro_calib_data[0].abs_code = ABS_RX;
-	ds4->gyro_calib_data[0].bias = gyro_pitch_bias;
+	ds4->gyro_calib_data[0].bias = 0;
 	ds4->gyro_calib_data[0].sens_numer = speed_2x*DS4_GYRO_RES_PER_DEG_S;
-	ds4->gyro_calib_data[0].sens_denom = gyro_pitch_plus - gyro_pitch_minus;
+	ds4->gyro_calib_data[0].sens_denom = abs(gyro_pitch_plus - gyro_pitch_bias) +
+			abs(gyro_pitch_minus - gyro_pitch_bias);
 
 	ds4->gyro_calib_data[1].abs_code = ABS_RY;
-	ds4->gyro_calib_data[1].bias = gyro_yaw_bias;
+	ds4->gyro_calib_data[1].bias = 0;
 	ds4->gyro_calib_data[1].sens_numer = speed_2x*DS4_GYRO_RES_PER_DEG_S;
-	ds4->gyro_calib_data[1].sens_denom = gyro_yaw_plus - gyro_yaw_minus;
+	ds4->gyro_calib_data[1].sens_denom = abs(gyro_yaw_plus - gyro_yaw_bias) +
+			abs(gyro_yaw_minus - gyro_yaw_bias);
 
 	ds4->gyro_calib_data[2].abs_code = ABS_RZ;
-	ds4->gyro_calib_data[2].bias = gyro_roll_bias;
+	ds4->gyro_calib_data[2].bias = 0;
 	ds4->gyro_calib_data[2].sens_numer = speed_2x*DS4_GYRO_RES_PER_DEG_S;
-	ds4->gyro_calib_data[2].sens_denom = gyro_roll_plus - gyro_roll_minus;
+	ds4->gyro_calib_data[2].sens_denom = abs(gyro_roll_plus - gyro_roll_bias) +
+			abs(gyro_roll_minus - gyro_roll_bias);
 
 	/*
 	 * Sanity check gyro calibration data. This is needed to prevent crashes
@@ -2241,8 +2244,7 @@ static int dualshock4_parse_report(struct ps_device *ps_dev, struct hid_report *
 	for (i = 0; i < ARRAY_SIZE(ds4_report->gyro); i++) {
 		int raw_data = (short)le16_to_cpu(ds4_report->gyro[i]);
 		int calib_data = mult_frac(ds4->gyro_calib_data[i].sens_numer,
-					   raw_data - ds4->gyro_calib_data[i].bias,
-					   ds4->gyro_calib_data[i].sens_denom);
+					   raw_data, ds4->gyro_calib_data[i].sens_denom);
 
 		input_report_abs(ds4->sensors, ds4->gyro_calib_data[i].abs_code, calib_data);
 	}
-- 
2.38.1