/dev/hiddev0

Hans Fugal hans at fugal.net
Mon Nov 12 06:57:06 MST 2007


On Sun, 11 Nov 2007 at 18:20 -0700, Nathan wrote:
> On Sun, 2007-11-11 at 13:47 -0700, Andrew Jorgensen wrote:
> > Hello,
> > 
> > My sister-in-law, who's using Ubuntu 7.10, is doing medical
> > transcription.  They have this USB pedal they use to control a program
> > that plays back the audio.  The device is a standard USB HID Joystick
> > device that happens to only have three buttons.  The company that
> > makes the software she's supposed to use has a linux version.  This
> > software looks for a pedal at /dev/hiddev*.  Ubuntu creates an input
> > device, /dev/input/js0, which not only isn't in the right place but is
> > an input device rather than a hiddev device.
> > 
> > Is there some way I can get a hiddev device out of this thing?  I
> > imagine the answer involves udev somehow but I'm lost as to how to get
> > it to create a device that accepts the HID ioctls.
> 
> It is just a simple udev rule.  In /etc/udev/rules.d you can create a
> new file named what ever you want ending with .rules.  Then you put a
> line like this in there:
> 
> BUS=="usb", KERNEL=="js*", NAME="hiddev%n"

That works if a symlink would work, which would be a temporary solution
and an easy check. But if the problem is that the joystick driver
should leave it alone so the hid driver can take it, it wouldn't. (I
don't know if this is the case or not). In that case, though, I think
you can use a udev rule to have the joystick driver ignore that
particular device.

After a quick google, it looks like hiddev and joystick can't both have
it, so if it's being detected as a joystick you need to tell it to buzz
off. If no other joysticks are used, you might try blacklisting the
joydev module, otherwise I'm sure there's a udev rule you can apply.

http://osdir.com/ml/sysutils.apcupsd.user/2004-11/msg00058.html


-- 
Hans Fugal ; http://hans.fugal.net
 
There's nothing remarkable about it. All one has to do is hit the 
right keys at the right time and the instrument plays itself.
    -- Johann Sebastian Bach



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