[Linuxwacom-devel] Changes/fixes to the ISDv4 protocol?

[Rene v. P. <ren...@gm...>]

Hi all,

I sent a message here a few days ago, and that did not generate much
response. So I went ahead and did what I thought was best.

The issue I had was that the wacom driver for the tablet PC's (Toshiba
Portege M700) we bought for our flight test instrumentation system did
not work for me. I sent the message to see if there were "worksforme"
responses, but I did not see any, and I found only more problem
reports by others with similar hardware.

So, I started to dig, and found:

1) The baud speed at which the driver was programming the serial port
was too low. A setting of 38400 works fine

2) Initial reading of the serial port at low speed failed. The
response programmed in the code was to re-open the port with a higher
speed (in isdv4GetRanges), but the code subsequently did not re-read
the configuration; the result is an invalid range, a nice divide by 0
and a crash at using the pen.

3) The handling of pen and touch (finger) data was not working. I
re-wrote most of isdv4Parse.

The result (for me), is a perfectly working pen and finger (touch)
input device. Both stylus and eraser are OK, stylus does button 1 and
2, eraser only 1, both correctly do pressure. Touch input is OK, but
of course has only button 1. Proximity events are properly sent (it
was quite a puzzle to eliminate dragging effects for the touch input
when touching different spots on the screen). This works under
OpenSuse 10.3 xorg-x11-server 7.2

The only thing that could be improved is that now the touch
coordinates use a fixed range (4096), which is mapped to the pen
range, and that no user-configurable corrections to scaling are
possible. I gladly leave that bit to anyone interested.

I am attaching two files, one is the (slightly updated) python script
that I used to debug the pen messages, and the other is a patch (on
wcmISDV4.c and the ChangeLog).

Of course, there might be machines for which the current wcmISDV4.c
file works flawlessly, and I have been dealing with a different
version of the protocol, in that case feel free to use this patch for
adding that new protocol.

here is the configuration from xorg.conf:
---------------------------

Section "InputDevice"
    Driver "wacom"
    Identifier "cursor"
    Option "Device" "/dev/ttyS0"
    Option "Type" "cursor"
    Option "Mode" "absolute"
    Option "debuglevel" "8"
    Option "ForceDevice" "ISDV4"
EndSection

Section "InputDevice"
    Driver "wacom"
    Identifier "stylus"
    Option "Device" "/dev/ttyS0"
    Option "Mode" "absolute"
    Option "Type" "stylus"
    Option "debuglevel" "8"
    Option "ForceDevice" "ISDV4"
EndSection

Section "InputDevice"
    Driver "wacom"
    Identifier "eraser"
    Option "Device" "/dev/ttyS0"
    Option "Type" "eraser"
    Option "Mode" "absolute"
    Option "debuglevel" "8"
    Option "ForceDevice" "ISDV4"
EndSection

---------------------------

Greetings,

Rene