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Input: resistive-adc-touch - fix division by zero error on z1 == 0

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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: 60b7db914d ("Input: resistive-adc-touch - rework mapping of channels")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20211007095727.29579-1-o.rempel@pengutronix.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Oleksij Rempel 2021-10-15 21:12:06 -07:00 committed by Dmitry Torokhov
parent d997cc1715
commit fe0a7e3d01
1 changed files with 16 additions and 13 deletions
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29
drivers/input/touchscreen/resistive-adc-touch.c
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@ -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))) {