Created attachment 27601 [details]
Xorg.0.log

XWarpPointer + synaptics touchpad = extreme cursor jumping

I have here a ThinkPad R61 7733A82 with a synaptics touchpad and a trackpoint.

If I generate some pointer events (button presses or movements) with the
touchpad and then do an XWarpPointer call, then the very next pointer event,
regardless of source or type, causes the pointer to immediately slam into the
extreme lower-right corner of the screen. However, if the last pointer event
before the XWarpPointer came from the trackpoint, then I don't get the cursor
jumping.

The pointer operates normally otherwise, even after the abnormal jump.

So, for example, if I move the cursor with the touchpad and then run a trivial
program that does:
	XWarpPointer(display, None, None, 0, 0, 0, 0, 10, 10);
Then pressing any mouse button or trying to move the cursor with either the
trackpoint or the touchpad causes the undesirable cursor jump.

However, if I move the cursor a bit with the trackpoint and then do the
XWarpPointer, then I don't get the jumping.

This bug is present regardless of which driver I use with the touchpad
(synaptics or evdev).

Both the synaptics and evdev drivers produce this behavior.

I've done some playing with gdb, and here's a bit that looks interesting to me:

Break in updateFromMaster, right before updateSlaveDeviceCoords. XWarpPointer
is the only thing I've seen that satisfies this breakpoint condition.

> (gdb) break getevents.c:641 if master == dev
> (gdb) commands
> >bt
> >printf "Min/max/val: %d %d %d\n", master->valuator->axes->min_value, \
>   master->valuator->axes->max_value, master->last.valuators[0]
> >continue
> >end
> (gdb) break getevents.c:642 if master == dev
> (gdb) commands
> >printf "Min/max/val: %d %d %d\n", master->valuator->axes->min_value, \
>   master->valuator->axes->max_value, master->last.valuators[0]
> >continue
> >end
> (gdb) continue
> 
> # Move cursor around with the touchpad, then do a XWarpPointer
> [Switching to Thread 0x7f11e25d5700 (LWP 2912)]
> Breakpoint 1, updateFromMaster (events=0x5367610, dev=0x51e7e20, type=4, 
>     num_events=0x7fff8064f0e4) at getevents.c:641
> 641             CreateClassesChangedEvent(events, master, dev, type);
> #0  updateFromMaster (events=0x5367610, dev=0x51e7e20, type=4, 
>     num_events=0x7fff8064f0e4) at getevents.c:641
> #1  0x000000000044db1c in GetPointerEvents (events=0x5367610, pDev=0x51e7e20, 
>     type=6, buttons=0, flags=20, first_valuator=0, num_valuators=2, 
>     valuators=0x7fff8064f140) at getevents.c:1066
> #2  0x000000000045b809 in miPointerWarpCursor (pDev=0x51e7e20, 
>     pScreen=0x245dfe0, x=427, y=579) at mipointer.c:580
> #3  0x00000000004875e0 in xf86WarpCursor (pDev=0x51e7e20, pScreen=0x245dfe0, 
>     x=427, y=579) at xf86Cursor.c:473
> #4  0x000000000045b53c in miPointerSetCursorPosition (pDev=0x51e7e20, 
>     pScreen=0x245dfe0, x=427, y=579, generateEvent=1) at mipointer.c:239
> #5  0x00000000005664ce in AnimCurSetCursorPosition (pDev=0x51e7e20, 
>     pScreen=0x245dfe0, x=427, y=579, generateEvent=1) at animcur.c:277
> #6  0x000000000042b303 in ProcWarpPointer (client=<value optimized out>)
>     at events.c:3341
> #7  0x0000000000448fe4 in Dispatch () at dispatch.c:426
> #8  0x0000000000426995 in main (argc=10, argv=0x7fff8064f478,
>     envp=<value optimized out>) at main.c:283
> 
> Min/max/val: 1472 5472 417
> 
> Breakpoint 2, updateFromMaster (events=0x5367610, dev=0x51e7e20, 
>     type=<value optimized out>, num_events=0x7fff8064f0e4) at getevents.c:643
> 643             master->last.slave = dev;
> 
> Min/max/val: 1472 5472 2774

Move pointer with (say) the trackpoint, and *bam*, slammed into the corner.
Notice that master->last.valuators[0] when from '417' to '2774' thanks to
the updateSlaveDeviceCoords call.

Now, move cursor around with the *trackpoint*, then do a XWarpPointer:

> Breakpoint 1, updateFromMaster (events=0x5367610, dev=0x51e7e20, type=4, 
>     num_events=0x7fff8064f0e4) at getevents.c:641
> 641             CreateClassesChangedEvent(events, master, dev, type);
> #0  updateFromMaster (events=0x5367610, dev=0x51e7e20, type=4, 
>     num_events=0x7fff8064f0e4) at getevents.c:641
> #1  0x000000000044db1c in GetPointerEvents (events=0x5367610, pDev=0x51e7e20, 
>     type=6, buttons=0, flags=20, first_valuator=0, num_valuators=2, 
>     valuators=0x7fff8064f140) at getevents.c:1066
> #2  0x000000000045b809 in miPointerWarpCursor (pDev=0x51e7e20, 
>     pScreen=0x245dfe0, x=328, y=555) at mipointer.c:580
> #3  0x00000000004875e0 in xf86WarpCursor (pDev=0x51e7e20, pScreen=0x245dfe0, 
>     x=328, y=555) at xf86Cursor.c:473
> #4  0x000000000045b53c in miPointerSetCursorPosition (pDev=0x51e7e20, 
>     pScreen=0x245dfe0, x=328, y=555, generateEvent=1) at mipointer.c:239
> #5  0x00000000005664ce in AnimCurSetCursorPosition (pDev=0x51e7e20, 
>     pScreen=0x245dfe0, x=328, y=555, generateEvent=1) at animcur.c:277
> #6  0x000000000042b303 in ProcWarpPointer (client=<value optimized out>)
>     at events.c:3341
> #7  0x0000000000448fe4 in Dispatch () at dispatch.c:426
> #8  0x0000000000426995 in main (argc=10, argv=0x7fff8064f478, 
>     envp=<value optimized out>) at main.c:283
> 
> Min/max/val: -1 -1 318
> 
> Breakpoint 2, updateFromMaster (events=0x5367610, dev=0x51e7e20, 
>     type=<value optimized out>, num_events=0x7fff8064f0e4) at getevents.c:643
> 643             master->last.slave = dev;
> 
> Min/max/val: -1 -1 318

I note that in this case, the coordinate value is unchanged.


Environment:
Ubuntu 9.04 amd64
Kernel: 2.6.31-rc2-00079-gdc53fff
xserver, Xlib, xf86-input-evdev, and just about everything else xorg-related:
   current git

Xorg.0.log attached.

HTH!