iio: imu: inv_mpu6050: clean set_power_itg and fix usage

Rewrite set_power_itg. Failing when turning power off is
no more decreasing the counter now and sleeping only happens
when effectively turning the chip on. Fix also usage in init
function (setting power on one time is sufficient to ensure
chip is effectively on).
Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/inv_mpu6050/inv_mpu_core.c

@@ -191,26 +191,29 @@ int inv_mpu6050_switch_engine(struct inv_mpu6050_state *st, bool en, u32 mask)
 
 int inv_mpu6050_set_power_itg(struct inv_mpu6050_state *st, bool power_on)
 {
-	int result = 0;
+	int result;
 
 	if (power_on) {
-		if (!st->powerup_count)
+		if (!st->powerup_count) {
 			result = regmap_write(st->map, st->reg->pwr_mgmt_1, 0);
-		if (!result)
+			if (result)
+				return result;
+			usleep_range(INV_MPU6050_REG_UP_TIME_MIN,
+				     INV_MPU6050_REG_UP_TIME_MAX);
+		}
 		st->powerup_count++;
 	} else {
-		st->powerup_count--;
-		if (!st->powerup_count)
+		if (st->powerup_count == 1) {
 			result = regmap_write(st->map, st->reg->pwr_mgmt_1,
 					      INV_MPU6050_BIT_SLEEP);
-	}
-
 			if (result)
 				return result;
+		}
+		st->powerup_count--;
+	}
 
-	if (power_on)
-		usleep_range(INV_MPU6050_REG_UP_TIME_MIN,
-			     INV_MPU6050_REG_UP_TIME_MAX);
+	dev_dbg(regmap_get_device(st->map), "set power %d, count=%u\n",
+		power_on, st->powerup_count);
 
 	return 0;
 }
@@ -856,14 +859,11 @@ static int inv_check_and_setup_chip(struct inv_mpu6050_state *st)
 	msleep(INV_MPU6050_POWER_UP_TIME);
 
 	/*
-	 * toggle power state. After reset, the sleep bit could be on
-	 * or off depending on the OTP settings. Toggling power would
+	 * Turn power on. After reset, the sleep bit could be on
+	 * or off depending on the OTP settings. Turning power on
 	 * make it in a definite state as well as making the hardware
 	 * state align with the software state
 	 */
-	result = inv_mpu6050_set_power_itg(st, false);
-	if (result)
-		return result;
 	result = inv_mpu6050_set_power_itg(st, true);
 	if (result)
 		return result;
@@ -871,13 +871,17 @@ static int inv_check_and_setup_chip(struct inv_mpu6050_state *st)
 	result = inv_mpu6050_switch_engine(st, false,
 					   INV_MPU6050_BIT_PWR_ACCL_STBY);
 	if (result)
-		return result;
+		goto error_power_off;
 	result = inv_mpu6050_switch_engine(st, false,
 					   INV_MPU6050_BIT_PWR_GYRO_STBY);
 	if (result)
-		return result;
+		goto error_power_off;
 
-	return 0;
+	return inv_mpu6050_set_power_itg(st, false);
+
+error_power_off:
+	inv_mpu6050_set_power_itg(st, false);
+	return result;
 }
 
 int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,