Re: [Linuxwacom-discuss] Intuos4 and pointer jitter

[SHIRAKAWA A. <shi...@gm...>]

On 2009-12-22 20:23, Alexia Death wrote:

> Your result actually proves, that there is nothing wrong with linuxwacom
> drivers because for virtualbox USB they are bypassed completely and the
> windows driver handles raw usb data.

You're right in that the windows usb data is bypassed, but I don't see 
how this alone proves that there's nothing wrong with linuxwacom drivers.

> The part that I believe differs for you
> between native and virtual is the linux USB controller driver for you
> particular chipset. There seems to be some sort of a problem on that level.a

If it's not the linuxwacom drivers, it must be something like that, yes. 
Otherwise the difference between Linux and Windows (native or 
virtualized, same results) couldn't be explained.

> bug or an utilization difference that adds noise. I  dont know USB architecture
> too well, but If I was you I would test the tablet with an external powered
> hub in case there is a problem with providing power and perhaps try to force
> the driver to use an older 1.1 USB protocol.

I don't have an externally powered USB hub, but Wacom tablets have a 
very low energy consumption. I don't think that the amount of power the 
usb port can offer is the problem. I'll try using the 1.1 USB protocol 
if possible and check if the problem can be solved, but if it works it's 
a very ugly workaround (I rely heavily on USB mass storage instead, so I 
need USB to work at full speed).

> Most esoteric thing I can come up with is that you are using a CRT monitor
> that is used at different frequency&resolution between OSes and generates
> disturbing RF noise.

I use a fairly modern LCD monitor. Also, when the jitter problem occurs 
on Linux under VirtualBox in Windows, the screen resolution or any other 
related parameter isn't changed at all. I even tried using the tablet as 
far from the pc as the usb cable allows, but with no change in the jitter.

* * *

BY THE WAY, I just tried the same Ubuntu 9.10 64-bit USB live 
distribution on a dual core AMD Athlon X2 5200+, Nforce 430 Chipset, 3 
GB RAM in a different room with another LCD monitor, so completely 
different conditions/pc, and I've experienced exactly the same jitter 
problem I have here.

I don't know what to think anymore...
If it's the tablet, why under Windows it works perfectly it's beyond my 
comprehension. I also guess it's not an USB driver issue.

-- 
SHIRAKAWA Akira