Cursor does not move left/right using touchpad on 2.6.22-20080123.4 and newer master kernels

[Denver Gingerich]

On 2.6.22-20080123.4 and newer master kernels (specifically
2.6.22-20080123.4, 2.6.25-20080430.1, 2.6.25-20080501.2, and
2.6.25-20080501.3), the cursor cannot move from side to side with the
touchpad, only up and down.  Using a USB mouse works fine.

Here is an example X session:
1. start X, cursor is in the center of the screen; touchpad has not been touched
2. touch touchpad, cursor immediately jumps to the left side of the screen
3. move around on touchpad, cursor stays "stuck" to the left side of
the screen, but moves up and down relative to how much vertical
touchpad movement there is
4a. release finger from touchpad, cursor immediately jumps to the
top-left corner of the screen (this may not be exactly the top-left
corner, but it is always on the left-most column of pixels within the
top 50-100 rows of pixels)
4b. move finger across right edge of touchpad, cursor moves very
quickly from left to right across the screen (there appears to be a
small area between the touchpad and the right third of the drawing pad
where left to right motion is detected)

Performing steps 2-4 consistently gives the same results within the
same X session and across reboots.

The cursor moves correctly using the touchpad on the 2.6.22-20070815.3
master kernel.  When I get some time, I will look at the diffs between
20080123.4 and 20070815.3 to determine where the touchpad code changed
so I can reduce the number of kernels I need to test to find the
problem.  If someone wants to do the code search for me, I won't be
offended :).

Denver