Re: [Bluez-devel] Re: Jumpy cursor with Wacom Graphire Bluetooth

[Marcel Holtmann <marcel@holtmann.org>]

Hi Robert,

> > >                 String WACOM Pen Tablet
> > >         Attribute 0x0200
> > >                 UINT16 0x0100
> > >         Attribute 0x0201
> > >                 UINT16 0x056a
> > >         Attribute 0x0202
> > >                 UINT16 0x0081
> > >         Attribute 0x0203
> > >                 UINT16 0x0100
> > >         Attribute 0x0204
> > >                 Bool True
> > >         Attribute 0x0205
> > >                 UINT16 0x0002
> > > siemer@panorama:~$ 
> > 
> > so this uses USB vendor and product ids of 056a:0081. So only thing that
> > makes me worry is, that all USB based Wacom tablets are blacklisted in
> > the hid-core.c file in the Linux kernel. Maybe there is a reason for it
> > and you need some crappy X-Window driver to make it work correctly.
> 
> I am (or was :-) in contact with the usb wacom driver author and people
> working for Wacom. There is working support for all the other Wacom
> tablets (which are USB devices). From what I read you have to patch some
> related drivers just to make sure they don't pick up the tablets as
> mice... - They do work fine with the "mouse"-drivers but obviously don't
> get everyting out of the tablet (first: absolute coordinates, pressure,
> etc.).

I realized that the kernel is using its own driver for the Wacom tablets
to make it working. I am sure you found the website for this driver. If
not, here it is:

	http://linuxwacom.sourceforge.net/

> So, Wacom told me that the Bluetooth tablet has two modes (at least): a
> normal HID one, and a "report wacom data" one. I'm trying to verify that
> the HID mode works actually okay...
> 
> On my list is:
> -getting HID mode to work well
> -investigate why encryption and authentification don't work right
> -setting wacom mode
> 
> (maybe I reorder it a bit... :-)

The encryption and authentication should be no problem at all. I used
this for most devices, but it is off for a mouse or pointer like device
by default. The reason is that these devices can't input their PIN and a
default PIN is weak anyhow.

Check with "hcidump -X -V" what happens.

> I have already the offer of the usb driver maintainer to take over
> development once the device is in wacom mode... - because of the wacom
> specific stuff and he doesn't know bluetooth well.

That might be the problem. Bluetooth is not USB and it works totally
different, even if both use the same HID specification. The only sane
thing here might be a good hiddev replacement. However this is nothing
that will happen very soon.

> The switch between the modes is done with a "set report mode feature"
> call. 

Question is what is default?

> > >         Attribute 0x0206
> > >                 Sequence
> > >                         Sequence
> > >                                 UINT8 0x22
> > >                                 String 05 01 09 02 a1 01 85 02 09 01 a1
> > > 00 05 09 19 01 29 03 15 00 25 01 95 03 75 01 81 02 95 01 75 05 81 01 05
> > > 01 09 30 09 31 09 38 15 81 25 7f 75 08 95 03 81 06 c0 c0 05 0d 09 01 a1
> > > 01 85 03 a1 00 06 00 ff 09 01 15 00 26 ff 00 75 08 95 07 81 02 c0 09 02
> > > 85 03 95 01 b1 02 09 03 85 04 95 01 b1 02 09 04 85 05 95 01 b1 02 09 05
> > > 85 06 95 01 b1 02 09 06 85 07 95 01 b1 02 09 07 85 08 95 01 b1 02 09 08
> > > 85 09 95 01 b1 02 c0
> > 
> > Nothing special in here, but someone should decode the report descriptor
> > to see what this device expects.
> 
> Du sprichst in Raetseln. What do you mean? Are you talking about the
> long "string"? - I will try to dig into the bluetooth sdp spec.

The attribute 0x0206 contains the report descriptor with id 0x22. This
descriptor defines the actual reports send from/to the device. This is
nothing SDP specific. It is pure HID, but Bluetooth holds this data in
the SDP database.

> > You wrote something about a switch. Is there a difference in the SDP
> > records if you choose a different setting?
> 
> I think I was talking about the two modes mentioned above. As hardware
> there are only buttons: two "mouse buttons", a power button and a
> "pairing" button.

What does the pairing button do? It makes the device discoverable and
pairable, right?

Regards

Marcel




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