Re: [Linuxwacom-discuss] Suprious inputs from my Wacom ArtZ II (UD-1212) serial tablet

[Vu N. S. <san...@la...>]

Hi Daniel

I'm not sure at all, but maybe this is the same issue I had with my serial 
tablet pc.
The message I posted (with a quick and dirty fix that works for me):

--------------------------------------------------------------------------------------------------------
[Linuxwacom-discuss] bad jumps and lines on Tablet PC

Some annoying bug with my Toshiba M750 tablet PC:

Regularly (every 5-10min or so), when I draw on the screen, I get a random 
jump of the cursor to some corner of the screen, resulting in a line drawn 
from where the stylus is to some edge of the screen.

I've been fighting with this until I decided to look at the drivers' sources...

So I have made a quick hack on the driver, which seems to work.
Warning : I'm not a professional programmer at all and I'm far from 
understanding the driver structure, so maybe I put it the the wrong place/file. 
Anyway it seems to work and it should not have side-effects if the threshold 
value is set high enough (2000 works for me)

* I've heard other people having the same trouble on this laptop. So I would 
favor including a hack like this in the driver official release.

* there's no such bug under Windows

San

PS: the patch does not solve the similar issue happening when you touch the 
touchpad and move your stylus as the same time. But this one is much less 
annoying.



Here is the patch, I guess this is self-explanatory:

--- linuxwacom-0.8.4-3/src/xdrv/wcmCommon.c     2009-09-16 21:54:04.000000000 
+0200
+++ linuxwacom-0.8.4-3-san/src/xdrv/wcmCommon.c 2009-11-12 10:59:54.000000000 
+0100
@@ -20,6 +20,10 @@
 #include "xf86Wacom.h"
 #include "../include/Xwacom.h"

+/* SAN -- the cursor should not move more that this threshold when in
+ * proximity */
+#define JUMP_THRESHOLD 2000
+
 /*
 #if XF86_VERSION_MAJOR < 4
  *
@@ -899,6 +903,19 @@
                x, y, z, v3, v4, v5, id, serial,
                is_button ? "true" : "false", buttons));

+       /* SAN */
+       /* tries to remove unwanted erratic jumps when in proximity */
+       if ( (is_proximity) & (priv->oldProximity) )
+         {
+           if ( (ABS(x - priv->oldX) + ABS(y- priv->oldY)) > JUMP_THRESHOLD )
+             {
+               DBG(2, priv->debugLevel, ErrorF("Suppress this jump !\n"));
+               x = priv->oldX;
+               y = priv->oldY;
+                 }
+         }
+       /* END - SAN */
+
        priv->currentX = x;
        priv->currentY = y;

Le dimanche 20 décembre 2009 08:24:55, Daniel Neville a écrit :
> G'day! Is there any way to make the Wacom ArtZ II (UD-1212) serial
> tablet work properly under Ubuntu? I'm running Ubuntu 8.04 at the
> moment.
> 
> It works fine except that it generates from time to time in the
> order of seconds to minutes, spurious click events at full force
> and often drags the pointer to the edge of the screen. Even using
> The GIMP just to scale an image is a race to complete the operation
> before a spurious event mars the image.
> 
> The spurious inputs do not occur when I'm running Windows on the
> same machine, so it seems unlikely to be a hardware fault.
> 
> Some of the spurious inputs do things I can't work out how to
> emulate with any stylus motion, tapping or side button clicks.
> I wonder if it's some event processing bug outside of the scope
> of the Linux Wacom driver.
> 
> Oddly, the spurious inputs are suppressed when I run xidump.
> I was considering running that continuously as a background
> task, but it doesn't seem to want to run forever.
> 
> wacdump does report some errors, though:
> 
> 20:14:14.570 INFO: Opening log
> 20:14:14.570 INFO: Setting baud rate to 38400
> 20:14:14.570 INFO: Sending reset
> 20:14:14.896 INFO: Setting baud rate to 19200
> 20:14:14.896 INFO: Sending reset
> 20:14:14.221 INFO: Setting baud rate to 9600
> 20:14:14.221 INFO: Sending reset
> 20:14:14.732 ERROR: LOBIT FAIL
> 20:14:14.733 WARN: Bad high bit, discarding 7 bytes
> 20:14:14.412 WARN: Bad high bit, discarding 1 bytes
> 20:14:14.420 WARN: Bad high bit, discarding 1 bytes
> 20:14:14.308 WARN: Bad high bit, discarding 1 bytes
> 20:14:14.316 ERROR: LOBIT FAIL
> 20:14:14.316 WARN: Bad high bit, discarding 5 bytes
> 20:14:14.328 WARN: Bad high bit, discarding 3 bytes
> 20:14:14.940 WARN: Bad high bit, discarding 1 bytes
> ...
> 
> ...and generates a storm of spurious events, possibly
> because it fights with the OS during the dump.
> 
> I was hoping for Ubuntu 9.10 to have some means of supporting the
> serial tablet directly. I gather it's all a bit of a mess at the
> moment with Xorg going out of fashion and then FDL files also being
> phased out in favour of Powerkit.
> 
> It's a shame that I can't use in Linux a tablet I've been using for
> more than ten years. It's built to last, rather like the Model M
> keyboard on my desk.
> 
> Any ideas how I could further diagnose and perhaps fix the problem?
>