[PATCH] iio: light: gp2ap020a00f: Fix signedness bug in gp2ap020a00f_get_thresh_reg()

[Alper Ak <alperyasinak1@gmail.com>]

gp2ap020a00f_get_thresh_reg() returns -EINVAL on error,
but it was declared as a u8.

Change the return type to int and update callers to use int type for
the return value and properly check for negative error codes.

Fixes: 5d6a25bad035 ("iio:gp2ap020a00f: Switch to new event config interface")
Signed-off-by: Alper Ak <alperyasinak1@gmail.com>
---
 drivers/iio/light/gp2ap020a00f.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/light/gp2ap020a00f.c b/drivers/iio/light/gp2ap020a00f.c
index c7df4b258e2c..9f2441fe8c52 100644
--- a/drivers/iio/light/gp2ap020a00f.c
+++ b/drivers/iio/light/gp2ap020a00f.c
@@ -992,7 +992,7 @@ static irqreturn_t gp2ap020a00f_trigger_handler(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
-static u8 gp2ap020a00f_get_thresh_reg(const struct iio_chan_spec *chan,
+static int gp2ap020a00f_get_thresh_reg(const struct iio_chan_spec *chan,
 					     enum iio_event_direction event_dir)
 {
 	switch (chan->type) {
@@ -1023,12 +1023,18 @@ static int gp2ap020a00f_write_event_val(struct iio_dev *indio_dev,
 	struct gp2ap020a00f_data *data = iio_priv(indio_dev);
 	bool event_en = false;
 	u8 thresh_val_id;
-	u8 thresh_reg_l;
+	int thresh_reg_l;
 	int err = 0;
 
 	mutex_lock(&data->lock);
 
 	thresh_reg_l = gp2ap020a00f_get_thresh_reg(chan, dir);
+
+	if (thresh_reg_l < 0) {
+		err = thresh_reg_l;
+		goto error_unlock;
+	}
+
 	thresh_val_id = GP2AP020A00F_THRESH_VAL_ID(thresh_reg_l);
 
 	if (thresh_val_id > GP2AP020A00F_THRESH_PH) {
@@ -1080,15 +1086,15 @@ static int gp2ap020a00f_read_event_val(struct iio_dev *indio_dev,
 				       int *val, int *val2)
 {
 	struct gp2ap020a00f_data *data = iio_priv(indio_dev);
-	u8 thresh_reg_l;
+	int thresh_reg_l;
 	int err = IIO_VAL_INT;
 
 	mutex_lock(&data->lock);
 
 	thresh_reg_l = gp2ap020a00f_get_thresh_reg(chan, dir);
 
-	if (thresh_reg_l > GP2AP020A00F_PH_L_REG) {
-		err = -EINVAL;
+	if (thresh_reg_l < 0) {
+		err = thresh_reg_l;
 		goto error_unlock;
 	}
 
-- 
2.43.0