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

Denver Gingerich denver at
Sun May 25 00:13:58 EDT 2008

On Sat, May 3, 2008 at 6:25 PM, Denver Gingerich <denver at> wrote:
> On Fri, May 2, 2008 at 10:42 PM, Denver Gingerich <denver at> wrote:
>> On Thu, May 1, 2008 at 11:38 PM, Denver Gingerich <denver at> wrote:
>>  > 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
> See below for more details on Step 2.
>>  >  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 problem is present in 2.6.22-2008115.1 but not in
>>  2.6.22-20080113.1.
> The problem is also present in 2.6.22-20080114.2.  So the problem is
> between the following commits:
> f8709785a433a5a3344304f9796fb26a65d69a1e
> cb6634de39d36cb9cc719c2940e456929ccceea2
> Here are some additional details for Step 2 (touch touchpad): the
> vertical position that the cursor jumps to is correlated with the
> location on the touchpad that my finger is on.  For example, if I
> touch the top part of the touchpad, the cursor will jump to the top
> part of the screen.  So there is some absolute positioning going on.
> Additionally, a button press is registered when I touch the touchpad
> (even when I don't click the button) and a button release is
> registered when I take my finger off the touchpad.  So moving my
> finger on the touchpad is essentially dragging whatever happens to be
> under the cursor.  The button press is registered after the cursor
> jumps to its new position on the screen following my finger touching
> the touchpad.

This issue is present in the 2.6.26-rc3 master kernel (not surprising
as mouse/olpc.c hasn't changed since 2.6.25).

I now have access to a development environment so I should be able to
compile the intermediate commits (between f870978 and cb6634d) to
diagnose the problem further.  I will report back when I have more


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