[PATCH V3] iio: gp2ap020a00f: Fix signedness bug

[Haowen Bai <baihaowen@meizu.com>]

function gp2ap020a00f_get_thresh_reg() is unsigned but returning -EINVAL
errcode, and thresh_reg_l is unsigned but receiving -EINVAL errcode. so
we have to change u8 -> int. Also we need to do index bound check at
gp2ap020a00f_read_event_val().

Signed-off-by: Haowen Bai <baihaowen@meizu.com>
---
V1->V2: s8 is not enough to hold an (arbitrary) error code. To be on the safe
side we need to use int.
V2->V3: add bound check at gp2ap020a00f_read_event_val().


 drivers/iio/light/gp2ap020a00f.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/light/gp2ap020a00f.c b/drivers/iio/light/gp2ap020a00f.c
index b820041159f7..f80d30786035 100644
--- a/drivers/iio/light/gp2ap020a00f.c
+++ b/drivers/iio/light/gp2ap020a00f.c
@@ -994,7 +994,7 @@ 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) {
@@ -1025,7 +1025,7 @@ 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);
@@ -1082,14 +1082,14 @@ 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) {
+	if (thresh_reg_l < 0 || thresh_reg_l > GP2AP020A00F_PH_L_REG) {
 		err = -EINVAL;
 		goto error_unlock;
 	}
-- 
2.7.4