Re: [PATCH 3/4] Fix "pointer jumps to corner of screen" problem on ALPS Glidepoint touchpads.

[Peter Osterlund <petero2@telia.com>]

Giuseppe Bilotta <bilotta78@hotpop.com> writes:

> Peter Osterlund wrote:
> > Only parse a "z == 127" packet as a relative Dualpoint stick packet if
> > the touchpad actually is a Dualpoint device.  The Glidepoint models
> > don't have a stick, and can report z == 127 for a very wide finger. If
> > such a packet is parsed as a stick packet, the mouse pointer will
> > typically jump to one corner of the screen.
> 
> I remember reading specs of a touchpad (can't remember if it 
> was ALPS or Synaptics) (driver) which could do "palm 
> detection" (basically ignoring events when a large part of the 
> hand accidentally touched/pressed the pad, FWICS).

Some synaptics touchpads can do palm detection in firmware, but the
software driver has to decide if the corresponding events shall be
ignored or not.

Anyway, this is unrelated to the patch. Without this patch, the packet
from the touchpad will be parsed incorrectly as a very big stick
motion, so a higher level driver (such as the X driver) can't really
see that there might be a palm touching the pad.

-- 
Peter Osterlund - petero2@telia.com
http://web.telia.com/~u89404340