Created attachment 43899 [details]
logfile after repair with 42-synaptics.conf applied

Hi, first time bug-reporter here...

Submitted this report at bugs.debian.org first, #615582, but they (KiBi) suggested to report it here instead. Here goes:

Sid saw a kernel upgrade from 2.6.32 to 2.6.37 two weeks ago
(?). Since then the touchpad on my Acer Travelmate 8571 doesn't work
as before: the vertical scroll action sometimes works for one stroke,
and then doesn't respond anymore. Single-tapping doesn't reliably
generate TapButton1 events, but most often TapButton3.
After booting back into kernel 2.6.32, everything is fine again.

Using "synclient -l" after booting one or the other kernel, I find different settings:

$ diff synclient_2.6.32.log synclient_2.6.37.log 
2,5c2,5
<     LeftEdge                = 1752
<     RightEdge               = 5192
<     TopEdge                 = 1620
<     BottomEdge              = 4236
---
>     LeftEdge                = 1762
>     RightEdge               = 5338
>     TopEdge                 = 1654
>     BottomEdge              = 4682
10c10
<     MaxTapMove              = 221
---
>     MaxTapMove              = 239
17,19c17,19
<     EmulateTwoFingerMinW    = 7
<     VertScrollDelta         = 100
<     HorizScrollDelta        = 100
---
>     EmulateTwoFingerMinW    = 6
>     VertScrollDelta         = 108
>     HorizScrollDelta        = 108
27c27
<     AccelFactor             = 0.0398089
---
>     AccelFactor             = 0.0367242
32c32
<     EdgeMotionMaxSpeed      = 401
---
>     EdgeMotionMaxSpeed      = 435
52c52
<     PalmMinWidth            = 10
---
>     PalmMinWidth            = 9

I have no /etc/X11/xorg.conf, i.e. all settings are read from
/usr/share/X11/xorg.conf.d/50-synaptics.conf:

Section "InputClass"
        Identifier "touchpad catchall"
        Driver "synaptics"
        MatchIsTouchpad "on"
EndSection

The surprising finding (to me) was in /var/log/Xorg.o.log. 

for kernel 2.6.32
(--) SynPS/2 Synaptics TouchPad: x-axis range 1472 - 5472
(--) SynPS/2 Synaptics TouchPad: y-axis range 1408 - 4448

whereas for kernel 2.6.37
(--) SynPS/2 Synaptics TouchPad: x-axis range 1472 - 5628
(--) SynPS/2 Synaptics TouchPad: y-axis range 1408 - 4928
  

So, the big question is: how are these different touchpad sizes "probed"?
I guess that the differnces reported by synclient are follow-up errors.
Manually setting the values back to what they were with 2.6.32
restores the desired behaviour. (e.g synclient "RightEdge" "5192") 
Or more permanenty by creating a conf file:

$ cat /etc/X11/xorg.conf.d/42-synaptics.conf
Section "InputClass"
    Identifier "touchpad tweaked catchall"
    MatchIsTouchpad "on"
    Driver "synaptics"
    Option "LeftEdge" "1752"
    Option "RightEdge" "5192"
    Option "MaxTapMove" "221"
    Option "EmulateTwoFingerMinW" "7"
    Option "PalmMinWidth" "10"
EndSection
 
Any help / advice appreciated!
Klaus