Bug#424743: X11 pen driver doesn't work on tabletPC Fujitsu Stylistic 2300 (fix included)
>
> 1.1.0 is still the latest upstream release, but 3 big
patches have been
> committed upstream since then (see
>
http://gitweb.freedesktop.org/?p=xorg/driver/xf86-input-fpit.git).
> PROXIMITY is still set to 0x20, but the code has
moved/changed. So it
> would be good to test it before complaining to upstream
about your bug.
> Is there a chance you try building the upstream git repository?
>
about the latest relese (named "update from J Blanchard part
3" . at first it didn't compile. I replaced
-----
*x = xf86ScaleAxis(v0, 0, priv->screen_width,
axes[0].min_value, axes[0].max_value);
*y = xf86ScaleAxis(v1, 0, priv->screen_height,
axes[1].min_value, axes[1].max_value);
----
by
----
*x = xf86ScaleAxis(v0, 0, priv->screen_width, priv->fpitMinX,
priv->fpitMaxX);
*y = xf86ScaleAxis(v1, 0, priv->screen_height, priv->fpitMinY,
priv->fpitMaxY);
----
it may break the screen rotation feature introduced by Justin
in this release.
Here is the behavior : the cursor wanders erratically on the
screen whenever I approach the pen. about 1 event on 5 is
correctly positionned although its not regular.
Surprisingly, when the system has some cpu(?) load, the pen
just works fine, and the cursor follow it.
for example, To make it work fine, I just need to launch a "
while (true) do true; done" on some console screen. It's
directly related. also works with heavy X apps, or during app
loading time.
After some tickling with the code, It appears that the Xorg
core function xf86ReadSerial(), used in the core of the
module, gives faulty results when the system is quite idle.
I've added some debug messages around this function, and the
data read from the serial device is correct when the system is
under load, but some Bytes are duplicated or NULL are added
when the system is at low pace. Therefore, absurd values are
read from those bytes and most coordinates are wrong.
I didn't spot any repeated pattern or anything regular: or
the errors seems inserted at random.
The erratic-ness is _proportionnal_ to the load.
(Adding too heavy debug messages puts loads on the system, and
the bug disappear...)
I've tried adjusting serial parameters values line 562, namely
Vmin and Vtime, to no avail; but I'm not skilled there and it
may still need some tweaking.
The command-line program pentest.c, gives perfect results,
load or not load. so it is not the pen/screen duo.
Tests are done using the same stty/setserial conf
even the oldest release of this file on gitweb give the same
erratic behavior: the core of the program didn't changed.
All of this was done with PROXIMITY at 0x20, so I was wrong,
it is not the point.
This behavior happened before sometimes, and thinking of it,
it was always related to the load. When running, my main
application eats a bit of cpu, that is why it does not happen
that often in running state. I'm switching to a new one, less
hungry, so the bug resurfaced.
the tabletPC is a fujitsu 2300 with an _active_ pen. a comment
from 2005 speaks about possible broken support for active pen
tablets...
Any pointers welcomed, especially on _X11_ serial
configuration (Vtime, Vmin and all) or a xf86ReadSerial()
replacement.
jean-marc Bourdaret
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