getting my new graphic tablet cooperating with gimp

[Markus Brueffer]

Am Mittwoch, 13. Februar 2008 18:28:09 schrieb Chuck Robey:
> Torfinn Ingolfsen wrote:
> > On Sun, 10 Feb 2008 18:10:52 +0100
> >
> > Kai Wang <kaiwang27 at gmail.com> wrote:
> >> On Sat, Feb 09, 2008 at 05:27:55PM -0500, Chuck Robey wrote:
> >>> I have a nice new UC-Logic WP8060-TAB08, sometimes called the
> >>> Superpen, and I want to get it working so's I can make fine art
> >>> with it (yeah, I'm a dreamer, so what else is new, hey?)  The
> >>> return off of dmesg is:
> >>>
> >>> ums0: <UC-LOGIC Tablet WP8060U, class 0/0, rev 1.10/0.00, addr 2>
> >>> on uhub0 ums0: X report 0x0002 not supported
> >>> device_attach: ums0 attach returned 6
> >>
> >> This is because your tablet use absolute coordinates (most tablets do)
> >> while ums(4) currently only support relative ones.
> >>
> >> Could you please try to dump your pen's report descriptor and paste it
> >> here, thus we can have more infomation?
>
> I appreciate the extra information.  In fact, I am having one heck of a
> time trying to figure out exactly how to parse this.  I am reading with the
> HID1_11 spec on my knee at all times, but I swear, I have never seen such a
> poorly written document!

It's not _that_ bad, but it surely lacks several clarifications in some areas 
and some information on specific topics is scattered across the whole 
document.

Best thing to get started is IMHO to get an idea about what reports are and to 
get the raw report descriptor of a simple device (e.g. a mouse if it's not 
from a keyboard/mouse combo) and start decoding it by hand. The sources of 
the libusbhid parser might be of help as well, although it contains several 
bugs and isn't spec compliant in several cases, but it might get you an idea 
of what's going on. Furthermore playing with usbhidctl might be of help.

I have written a completly new fully spec compliant HID parser which is soon 
ready for public consumption as part of a new libhid. It contains many 
comments and should be easy to understand. The data representation directly 
takes the tree-like structure of a decoded report descriptor into account so 
that it's easy to write drivers that only handle one or more specific 
application collections. Furthermore physical descriptors are supported and 
the data handling functions hide the concept of report IDs so that it's less 
error prone to develop HID drivers (ums(4) e.g. doesn't support reports other 
than report 0 which is the reason that many of todays mice don't work). The 
parser itself will hopefully replace our current in-kernel HID parser.

> I am having a terrible time trying to figure out 
> the actual scope of each statement, which refers to what.  I don't run any
> piece of Windows stuff here, so many of the pieces of demo software I have
> found on the web do me no good.

I didn't find any windows software that really made it easier to understand 
the spec. It's IMHO easier to directly get your hands dirty and to read the 
code of an HID parser.

> I'm not giving up, I keep on making new discoveries, but if anyone knows of
> a description of HID that involves some real use of English, I sure would
> appreciate a pointer to it.

If you have any specific questions, please drop me a mail.

Markus
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