Press and Release event passed only at finger remove

[DDAAXX]

Hi,
I'm using a capacitive touchscreen with Atmel Maxtouch driver (atmel_mxt_ts.c).
It uses raw_input.
When I press the screen and wait, I have no event emitted by tslib.
When I remove my finger, I have at the same time the press and the release events.
If I test with ts_test, I see:

854.560940: 226 270 49
856.515562: 226 270 0

So it seems that the timestamps are correct (2 seconds from the first and the second event).
Where I can check to find why tslib wait for the release event before to send the press?

Thanks a lot
Dario

[aahong]

Yes, I got this problem is a IR touchscreen also, I think problem is caused by variance delta, it may view first press as noise and delay send the event.

It works normal if I comment out variance delta.

module pthres pmin=1
#module variance delta=30
module dejitter delta=100
module linear

I do not view tslib's code to find out how to fix this bug, please help.

[DDAAXX]

Thanks for your hint!
I tried and it is correct, without variance it works, so I think the problem is in the variance module.
If I'll find time I'll check inside the code...

[phishstang65]

Hey Guys, I am seeing this as well with the Atmel MXT Touchscreen driver. Have you guys figured out any bug with the variance delta or how to fix it without totally dropping the module? Thanks!

[robgreger]

Based upon the first post, the controller may only be reporting once when the screen is pressed and once when the screen is released. If that is the case, then the touch controller is doing a great job filtering noise and the variance filter isn't necessary. The dejitter filter might also be unnecessary.

Having said that, the variance filter could be rewritten to pass through the first touch event if sample size is one since no more data is forthcoming. If sample size > 1 then filter the data as usual.

[merge]

I tested this on a capacitive touchscreen too. Fixed in master now, so it'll be in tslib 1.2. If one of you could test again, this would be awesome, but I know it's been a long time. Anyways, I'll keep this open for a few days.

[merge]

Closed. In case of problems, I'm happy to see a new bug report against master or 1.2. thanks