[PATCH v1] Input: resistive-adc-touch - fix division by zero error on z1 == 0
From: Oleksij Rempel <o.rempel@pengutronix.de>
Date: 2021-10-07 09:57:45
For proper pressure calculation we need at least x and z1 to be non
zero. Even worse, in case z1 we may run in to division by zero
error.
Fixes: 60b7db914ddd ("Input: resistive-adc-touch - rework mapping of channels")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
.../input/touchscreen/resistive-adc-touch.c | 29 ++++++++++---------
1 file changed, 16 insertions(+), 13 deletions(-)
diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c
index 744544a723b7..6f754a8d30b1 100644
--- a/drivers/input/touchscreen/resistive-adc-touch.c
+++ b/drivers/input/touchscreen/resistive-adc-touch.c@@ -71,19 +71,22 @@ static int grts_cb(const void *data, void *private) unsigned int z2 = touch_info[st->ch_map[GRTS_CH_Z2]]; unsigned int Rt; - Rt = z2; - Rt -= z1; - Rt *= st->x_plate_ohms; - Rt = DIV_ROUND_CLOSEST(Rt, 16); - Rt *= x; - Rt /= z1; - Rt = DIV_ROUND_CLOSEST(Rt, 256); - /* - * On increased pressure the resistance (Rt) is decreasing - * so, convert values to make it looks as real pressure. - */ - if (Rt < GRTS_DEFAULT_PRESSURE_MAX) - press = GRTS_DEFAULT_PRESSURE_MAX - Rt; + if (likely(x && z1)) { + Rt = z2; + Rt -= z1; + Rt *= st->x_plate_ohms; + Rt = DIV_ROUND_CLOSEST(Rt, 16); + Rt *= x; + Rt /= z1; + Rt = DIV_ROUND_CLOSEST(Rt, 256); + /* + * On increased pressure the resistance (Rt) is + * decreasing so, convert values to make it looks as + * real pressure. + */ + if (Rt < GRTS_DEFAULT_PRESSURE_MAX) + press = GRTS_DEFAULT_PRESSURE_MAX - Rt; + } } if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {
--
2.30.2