iio: imu: fxos8700: fix ACCEL measurement range selection

When device is in active mode, it fails to set an ACCEL full-scale
range(2g/4g/8g) in FXOS8700_XYZ_DATA_CFG. This is not align with the
datasheet, but it is a fxos8700 chip behavior.

Keep the device in standby mode before setting ACCEL full-scale range
into FXOS8700_XYZ_DATA_CFG in chip initialization phase and setting
scale phase.

Fixes: 84e5ddd5c4 ("iio: imu: Add support for the FXOS8700 IMU")
Signed-off-by: Carlos Song <carlos.song@nxp.com>
Link: https://lore.kernel.org/r/20221208071911.2405922-6-carlos.song@nxp.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/fxos8700_core.c

@@ -345,7 +345,8 @@ static int fxos8700_set_active_mode(struct fxos8700_data *data,
 static int fxos8700_set_scale(struct fxos8700_data *data,
 			      enum fxos8700_sensor t, int uscale)
 {
-	int i;
+	int i, ret, val;
+	bool active_mode;
 	static const int scale_num = ARRAY_SIZE(fxos8700_accel_scale);
 	struct device *dev = regmap_get_device(data->regmap);
 
@@ -354,6 +355,25 @@ static int fxos8700_set_scale(struct fxos8700_data *data,
 		return -EINVAL;
 	}
 
+	/*
+	 * When device is in active mode, it failed to set an ACCEL
+	 * full-scale range(2g/4g/8g) in FXOS8700_XYZ_DATA_CFG.
+	 * This is not align with the datasheet, but it is a fxos8700
+	 * chip behavier. Set the device in standby mode before setting
+	 * an ACCEL full-scale range.
+	 */
+	ret = regmap_read(data->regmap, FXOS8700_CTRL_REG1, &val);
+	if (ret)
+		return ret;
+
+	active_mode = val & FXOS8700_ACTIVE;
+	if (active_mode) {
+		ret = regmap_write(data->regmap, FXOS8700_CTRL_REG1,
+				   val & ~FXOS8700_ACTIVE);
+		if (ret)
+			return ret;
+	}
+
 	for (i = 0; i < scale_num; i++)
 		if (fxos8700_accel_scale[i].uscale == uscale)
 			break;
@@ -361,8 +381,12 @@ static int fxos8700_set_scale(struct fxos8700_data *data,
 	if (i == scale_num)
 		return -EINVAL;
 
-	return regmap_write(data->regmap, FXOS8700_XYZ_DATA_CFG,
+	ret = regmap_write(data->regmap, FXOS8700_XYZ_DATA_CFG,
 			    fxos8700_accel_scale[i].bits);
+	if (ret)
+		return ret;
+	return regmap_write(data->regmap, FXOS8700_CTRL_REG1,
+				  active_mode);
 }
 
 static int fxos8700_get_scale(struct fxos8700_data *data,
@@ -631,14 +655,17 @@ static int fxos8700_chip_init(struct fxos8700_data *data, bool use_spi)
 	if (ret)
 		return ret;
 
-	/* Max ODR (800Hz individual or 400Hz hybrid), active mode */
-	ret = regmap_write(data->regmap, FXOS8700_CTRL_REG1,
-			   FXOS8700_CTRL_ODR_MAX | FXOS8700_ACTIVE);
+	/*
+	 * Set max full-scale range (+/-8G) for ACCEL sensor in chip
+	 * initialization then activate the device.
+	 */
+	ret = regmap_write(data->regmap, FXOS8700_XYZ_DATA_CFG, MODE_8G);
 	if (ret)
 		return ret;
 
-	/* Set for max full-scale range (+/-8G) */
-	return regmap_write(data->regmap, FXOS8700_XYZ_DATA_CFG, MODE_8G);
+	/* Max ODR (800Hz individual or 400Hz hybrid), active mode */
+	return regmap_write(data->regmap, FXOS8700_CTRL_REG1,
+			   FXOS8700_CTRL_ODR_MAX | FXOS8700_ACTIVE);
 }
 
 static void fxos8700_chip_uninit(void *data)