evdev always returns fixed XY values

Peter Korsgaard peter at korsgaard.com
Fri May 22 06:28:59 PDT 2015


>>>>> "Marco" == Marco Cavallini <info at koansoftware.com> writes:

Hi,

 > The evtest returns values between ~4600 to ~7800
 > I touched min XY and max XY points.
 > xinput test returns always 4095.
 > Wat am I missing?

Looks like your touchscreen driver is buggy.

 > # evtest /dev/input/event0
 > Input driver version is 1.0.1
 > Input device ID: bus 0x0 vendor 0x0 product 0x0 version 0x0
 > Input device name: "ADS7843 Touchscreen"
 > Supported events:
 >   Event type 0 (EV_SYN)
 >   Event type 1 (EV_KEY)
 >     Event code 330 (BTN_TOUCH)
 >   Event type 3 (EV_ABS)
 >     Event code 0 (ABS_X)
 >       Value      0
 >       Min        0
 >       Max     4095
 >     Event code 1 (ABS_Y)
 >       Value      0
 >       Min        0
 >       Max     4095

Driver claims to return X/Y in 0..4095 range.

 > Event: time 1432134719.652423, type 3 (EV_ABS), code 0 (ABS_X), value 7823
 > Event: time 1432134719.652423, type 3 (EV_ABS), code 1 (ABS_Y), value 7987

But then returns values that are outside this range, confusing user space.

Garbage in is garbage out.

-- 
Bye, Peter Korsgaard


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