Bug 97194

Created attachment 125497 [details]
the rest

can you get me a shorter recording for this please? the jump is somewhere halfway into this recording which makes it a bit hard to isolate.

Created attachment 125512 [details]
one more

here it is, it happened only once at the end of the recording

urgh, this is still north of 1500 events to sift through. for next time, please keep it as short as possible, ideally only one sequence.

but something is seriously wrong with this touchpad. it suggests you recorded 40 finger sequences here but a large percentage of those have no or hardly any events. e.g. see 1.988464,  2.148737, 3.255834, 9.491922, 9.644970
This suggests that the hardware loses tracking here and thinks the finger is up when it is still down. Since I don't know what you did to get this recording I'm assuming you had the finger down for most of the time, just executing a couple of normal motions?

2.148737 shows up as a jump her but event-wise it looks like a normal (albeit) short touch.

12.063640 is the second jump (could be the one you referred to) and that is probably a bug. The issue here is that the finger starts on Y:138, the second finger sets down, finger 1 moves to 151 with two fingers down, then 178 in the same frame the second finger is released. The two finger movment doesn't trigger a gesture (probably not hitting the thresholds, doesn't matter anyway). The last Y event is in the same frame as the finger release and triggers a motion event (from 151 - 178 device coords) - that's the jump seen. Sequence ends at 12.200861.

The main question now is: is this the jump you're talking about? the one on 2-to-1 finger transition?

it is really dificult for me to capture it because it happens in a series.. some times there is no jumping at all for lets say 10 min, and sometimes cursor jumps 10 times In a row, last record took me 30 min because i wanted to capture shord period of time.
jumping is happening only when i tap with two fingers, my action was tapping few times with two fingers.

fwiw, if you grab evemu 2.4 or later it has a --autorestart option that creates new recordings after a given timeout. Set it to say 3 seconds and you'll get a new file whenever you don't use the touchpad for 3 seconds. This should make things a lot easier to capture.

(In reply to zetxx from comment #5)
> jumping is happening only when i tap with two fingers, my action was tapping
> few times with two fingers.

oh, ok. so is this the issue then, that the cursor jumps on two-finger taps? that would be a lot easier to detect and deal with.

(In reply to Peter Hutterer from comment #6)
> fwiw, if you grab evemu 2.4 or later it has a --autorestart option that
> creates new recordings after a given timeout. Set it to say 3 seconds and
> you'll get a new file whenever you don't use the touchpad for 3 seconds.
> This should make things a lot easier to capture.
> 
> (In reply to zetxx from comment #5)
> > jumping is happening only when i tap with two fingers, my action was tapping
> > few times with two fingers.
> 
> oh, ok. so is this the issue then, that the cursor jumps on two-finger taps?
correct
i will try to make another capture later today

note to self: what we probably need here is some feedback from the tapping code to tell us when a tap has been triggered. if so, we need a motion history reset on the touch to avoid the jump.

Created attachment 125623 [details] [review]
0001-touchpad-reset-the-motion-history-when-we-release-a-.patch

Please give this one a try and let me know how you go

sorry for the delay but unfortunately im on road and will check it after few days

closing this for now but please do reopen it if you find it didn't fix the issue

commit 3cb60130c182cb4bbfa8f908218fb12e84866cd5
Author: Peter Hutterer <peter.hutterer@who-t.net>
Date:   Thu Aug 4 15:23:43 2016 +1000

    touchpad: on a non-clickpad, reset the motion history on nfingers change