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From:   Dmitry Osipenko <digetx@gmail.com>
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <mirq-linux@rere.qmqm.pl>,
        Johnny Chuang <johnny.chuang.emc@gmail.com>,
        Jasper Korten <jja2000@gmail.com>,
        Svyatoslav Ryhel <clamor95@gmail.com>
Cc:     linux-input@vger.kernel.org, linux-tegra@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v1] Input: elants_i2c - fix division by zero if firmware reports zero phys size
Date:   Tue,  2 Mar 2021 13:08:24 +0300
Message-Id: <20210302100824.3423-1-digetx@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Touchscreen firmware of ASUS Transformer TF700T reports zeros for the phys
size. Hence check whether the size is zero and don't set the resolution in
this case.

Reported-by: Jasper Korten <jja2000@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---

Please note that ASUS TF700T isn't yet supported by upstream kernel,
hence this is not a critical fix.

 drivers/input/touchscreen/elants_i2c.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
index 4c2b579f6c8b..a2e1cc4192b0 100644
--- a/drivers/input/touchscreen/elants_i2c.c
+++ b/drivers/input/touchscreen/elants_i2c.c
@@ -1441,14 +1441,16 @@ static int elants_i2c_probe(struct i2c_client *client,
 
 	touchscreen_parse_properties(ts->input, true, &ts->prop);
 
-	if (ts->chip_id == EKTF3624) {
+	if (ts->chip_id == EKTF3624 && ts->phy_x && ts->phy_y) {
 		/* calculate resolution from size */
 		ts->x_res = DIV_ROUND_CLOSEST(ts->prop.max_x, ts->phy_x);
 		ts->y_res = DIV_ROUND_CLOSEST(ts->prop.max_y, ts->phy_y);
 	}
 
-	input_abs_set_res(ts->input, ABS_MT_POSITION_X, ts->x_res);
-	input_abs_set_res(ts->input, ABS_MT_POSITION_Y, ts->y_res);
+	if (ts->x_res > 0)
+		input_abs_set_res(ts->input, ABS_MT_POSITION_X, ts->x_res);
+	if (ts->y_res > 0)
+		input_abs_set_res(ts->input, ABS_MT_POSITION_Y, ts->y_res);
 	if (ts->major_res > 0)
 		input_abs_set_res(ts->input, ABS_MT_TOUCH_MAJOR, ts->major_res);
 
-- 
2.29.2