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SubjectRe: [PATCH v1] Input: elants_i2c - fix division by zero if firmware reports zero phys size
Hi Dmitry,

On Tue, Mar 02, 2021 at 01:08:24PM +0300, Dmitry Osipenko wrote:
> 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);

There is absolutely no difference between setting respluton to 0 vs not
setting it at all, so I dropped the conditionals and applied.

> + if (ts->y_res > 0)
> + input_abs_set_res(ts->input, ABS_MT_POSITION_Y, ts->y_res);
> if (ts->major_res > 0)

We could drop this condition as well.

> input_abs_set_res(ts->input, ABS_MT_TOUCH_MAJOR, ts->major_res);
>
> --
> 2.29.2
>

Thanks.

--
Dmitry

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