iio:pressure: preenable/postenable/predisable fixup for ST press buffer

This patch is trying to cleanup for good the buffers operation functions.
There is no need of using preenable, all can be done into
postenable. Let's also use logical sequence of operations as
already done in accel driver.
Finally also rename the goto label using operation to perform and not
where it fails.

Not stable material as not fixing a 'bug' but rather bringing the
driver in line with general 'patterns' to allow a subsystem wide
cleanup.
Signed-off-by: Denis Ciocca <denis.ciocca@st.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/pressure/st_pressure_buffer.c

@@ -29,53 +29,49 @@ int st_press_trig_set_state(struct iio_trigger *trig, bool state)
 	return st_sensors_set_dataready_irq(indio_dev, state);
 }
 
-static int st_press_buffer_preenable(struct iio_dev *indio_dev)
-{
-	return st_sensors_set_enable(indio_dev, true);
-}
-
 static int st_press_buffer_postenable(struct iio_dev *indio_dev)
 {
-	int err;
 	struct st_sensor_data *press_data = iio_priv(indio_dev);
+	int err;
 
 	press_data->buffer_data = kmalloc(indio_dev->scan_bytes,
 					  GFP_DMA | GFP_KERNEL);
-	if (press_data->buffer_data == NULL) {
-		err = -ENOMEM;
-		goto allocate_memory_error;
-	}
+	if (!press_data->buffer_data)
+		return -ENOMEM;
 
 	err = iio_triggered_buffer_postenable(indio_dev);
 	if (err < 0)
-		goto st_press_buffer_postenable_error;
+		goto st_press_free_buffer;
 
-	return err;
+	err = st_sensors_set_enable(indio_dev, true);
+	if (err < 0)
+		goto st_press_buffer_predisable;
+
+	return 0;
 
-st_press_buffer_postenable_error:
+st_press_buffer_predisable:
+	iio_triggered_buffer_predisable(indio_dev);
+st_press_free_buffer:
 	kfree(press_data->buffer_data);
-allocate_memory_error:
 	return err;
 }
 
 static int st_press_buffer_predisable(struct iio_dev *indio_dev)
 {
-	int err;
 	struct st_sensor_data *press_data = iio_priv(indio_dev);
-
-	err = iio_triggered_buffer_predisable(indio_dev);
-	if (err < 0)
-		goto st_press_buffer_predisable_error;
+	int err, err2;
 
 	err = st_sensors_set_enable(indio_dev, false);
 
-st_press_buffer_predisable_error:
+	err2 = iio_triggered_buffer_predisable(indio_dev);
+	if (!err)
+		err = err2;
+
 	kfree(press_data->buffer_data);
 	return err;
 }
 
 static const struct iio_buffer_setup_ops st_press_buffer_setup_ops = {
-	.preenable = &st_press_buffer_preenable,
 	.postenable = &st_press_buffer_postenable,
 	.predisable = &st_press_buffer_predisable,
 };