Re: cth-470 and Red Hat 6
Duffy, Peter <Peter.Duffy <at> echostar.com>
2012-02-02 16:47:30 GMT
Hi Chris,
OK, many thanks for the hints - I'll give it a go.
Regards,
Peter
-----Original Message-----
From: Chris Bagwell [mailto:chris <at> cnpbagwell.com]
Sent: 02 February 2012 16:05
To: Duffy, Peter
Cc: linuxwacom-discuss <at> lists.sourceforge.net
Subject: Re: [Linuxwacom-discuss] cth-470 and Red Hat 6
Hi Duffy,
Comments below.
On Thu, Feb 2, 2012 at 4:18 AM, Duffy, Peter <Peter.Duffy <at> echostar.com> wrote:
> Hi,
>
> Just wondering if anyone has got the Wacom Bamboo Pen & Touch
> (CTH-470) working under Red Hat Enterprise 6 (RHEL6) (or CentOS 6) -
> and if so, what procedure was followed?
>
> I've been trying for several weeks to get it working. One key problem
> that I'm hitting is that in the input-wacom driver source (I'm using
> 0.12.1), there are three separate source directories, one each for
> kernels 2.6.30,
> 2.6.36 and 2.6.38. The problem is that RHEL6 uses 2.6.32 only (Red Hat
> apparently merge in changes from later kernels and increment their own
> sub-modification number) and because of this, the input-wacom build
> picks up the 2.6.30 version of the driver source. But the CTH-470
> device (device id
> 0xDE) is only defined in the 2.6.38 source.
Correct. The biggest issue is that the Bamboo Pen and Touch series of tablets are multitouch tablets.
Multitouch can not be correctly supported in kernel drivers until 2.6.38 at least. So if your goal is
multitouch then you are out of luck.
I do not have access to a 2.6.30 kernel and why I've been unable to backport or support the effort directly. I
only have 2.6.38+ and thats why you see it only in that directory.
>
> This issue affects any distro which is based on Red Hat Enterprise
> (including CentOS and Scientific Linux) - but not Fedora Core, as this
> isn't limited to the single kernel version.
>
> Is there any chance that support for this device could be included in
> the 2.6.30 source? (I'd be happy to have a go at porting it across
> myself, if there's no obvious gotcha which would mean that it would be
> doomed to failure from the start. I realise that it wouldn't be
> trivial, as there seem to be large-scale changes between the 2.6.30
> and 2.6.38 drivers.)
I will be able to give you hints on how to get it working as long as your comfortable hacking kernel drivers.
If your interested in getting only the Stylus working then you could do that with small amount of effort.
The stylus packet sent from this 3rd gen Bamboo's is the same as format of 1st gen Bamboo's supported in the
2.6.30 input-wacom driver except for 1 bit.
In 2.6.30/wacom_wac.c, search for the phrase "0xD1" and you'll see two lines. Duplicate those two lines
and change 0xD1 to 0xD? that matches your tablets USB ID.
Next, search for function wacom_bpt_irq() and find this line:
} else if (len == WACOM_PKGLEN_BBFUN) { /* Penabled */
prox = (data[1] & 0x10) && (data[1] & 0x20);
and make it this shorter version:
prox = (data[1] & 0x20);
Now recompile and test that model out and see if the stylus works for you.
If you were doing this in the 2.6.36 driver, I think there is chance of divide by zero crash in
wacom_calculate_touch_res() because we are not initializing the touch structure with this simple
change. But that function doesn't exist in 2.6.30 so I think we are OK.
If you get it working this far and are interested in getting a non-multitouch version of touch working, then
let me know and I'll give hints for that as well.
>
> By the way - another interesting issue with RHEL6 and derivatives is
> that virtually all the documentation says that xorg > 1.7 uses udev
> for hot-plug devices - but this isn't the case in RHEL6: at least up
> to the latest supported version of xorg (1.10.4) it still uses hal. (It's easy to prove:
> reboot into runlevel 3, kill the hal service ("service haldaemon
> stop") and then start X: result - no mouse or keyboard.)
>
> Also by the way - someone's probably wondering why I don't just ditch
> the Red Hat kernel and instead use the latest 2.6 kernel built from
> source. Yes, I'd love to - but unfortunately it isn't an option, as
> our linux workstations run software which relies on the Red Hat kernel being present.
I can't remember know what bugs existed in xorg 1.10.4 or in older versions of xf86-input-wacom input
driver but I know there were fixes required to both those things before stylus+touch would work with it.
Your probably OK with any version as long as your testing only stylus.
Good luck,
Chris
>
> Regards,
> Peter
>
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