Heads up on touchpad change

[Andres Salomon]

On Sun, 6 Jul 2008 15:58:13 -0700
Deepak Saxena <dsaxena at laptop.org> wrote:

> On Jul 06 2008, at 07:46, Andres Salomon was caught saying:
> > 
[...]
> > 
> > I'm typing this email from an XO (the super-cranky Fred) that's
> > using a master kernel, and I'm pretty happy w/ the results.
> > Additional testing of master would be most welcome.
> > 
> 
> We should  push these patches into testing too. At this point
> we're not going to ship master for 8.2 and really need to have 
> a way to deal with buggy HW in the field.
> 
> ~Deepak
> 

Well, I was hoping for some testing, but if getting it in joyride is
the best way to accomplish that (and the release folks aren't going to
complain), then that's fine.  I'll go ahead and commit to testing.
Note that I'll be on a plane in a few hours, so I won't be responsive
until later tomorrow.

Cc'ing devel for a wider audience.  Basically, we've got a new touchpad
driver that uses mouse mode rather than advanced/stream mode.  This
means the PT won't work, but the benefits are numerous:

 - lots of silly complexity ripped out of the driver
 - smaller packet size means that deltas between packets are much much
smaller
 - smaller deltas means that it's much easier to detect jumpiness; i
found it impossible to get >90px deltas using my fingers, but i saw
150px deltas when the touchpad was freaking out
 - packets are only sent when a finger moves on the pad, rather than any
time a finger is placed down.  this makes it easier to detect when the
hardware starts spewing packets.  i've come up w/ a completely
different heuristic for detecting this, based upon what i've noticed.
i was unable to trigger any false-positives with this, so i'm much
happier.
 - no finger-up/finger-down packets, which is yet another hardware bug
that we don't have to deal w/.

The recalibration stuff requires a 2s window of silence after
occurrence, or it will keep trying to recalibrate until that is
satisfied.  There's the potential for shortening this, but I haven't
tested it yet.  Likewise, I also haven't tested the power toggling
stuff yet; I was hoping to get feedback on the other stuff, first.
Please test and report back!