Griffin Powermate evdev setup

Phil Endecott spam_from_xorg at
Mon Apr 27 03:00:55 PDT 2009

Dan Nicholson wrote:
> On Sun, Apr 26, 2009 at 4:09 PM, Phil Endecott
> <spam_from_xorg at> wrote:
>> I have a Griffin Powermate; it's a USB "knob" that you can use for
>> scrolling etc.  This morning the computer that it was attached to
>> died.  I'm now having trouble getting to work with the substitute machine.

>> (**) Griffin Powermate: always reports core events
>> (**) Griffin Powermate: Device: "/dev/input/by-id/usb-Griffin_Technology__Inc._Griffin_PowerMate-event-misc"
>> (WW) Griffin Powermate: Don't know how to use device
>> (II) UnloadModule: "evdev"
>> (EE) PreInit returned NULL for "Griffin Powermate"
>> So, what does "Don't know how to use device" mean?
> This means that the evdev driver didn't recognize it to be either a
> pointer, a keyboard or a touchscreen during it's probing routine.
> Looking at a photo online, I can't really tell how you'd classify it,
> but there could certainly be bugs in the detection logic. If you have
> the source, take a look in src/evdev.c:EvdevProbe. 
- Right?

This seems like a regression since the previous version of this driver, 
which was able to manage this device.  What can be done?

(BTW the kernel driver is here:;a=blob;f=drivers/input/misc/powermate.c)

Cheers,  Phil.

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