Too keen to use evdev (/dev/input/event%d) for joysticks, so ignores calibration

[Chris Boyle]

Binary package hint: libsdl1.2debian-alsa

I have a USB joystick which requires calibration (Saitek Cyborg 3D USB, ID 06a3:0006). I can calibrate it with jscal, but all SDL games (such as the Freespace port at http://scp.indiegames.us/ and the Descent port at http://icculus.org/d2x/ ) ignore the calibration. You can see why from the SDL source:

http://www.libsdl.org/cgi/viewvc.cgi/branches/SDL-1.2/src/joystick/linux/SDL_sysjoystick.c?view=markup
(look for "joydev_pattern" and "calibrate" in here)

SDL prefers to use /dev/input/event%d instead of /dev/input/js%d, even knowing there is no way to calibrate an event device. Therefore, if you have a joystick that (1) needs calibration and (2) also appears as an event device, you lose.

Workarounds:

 * Set SDL_JOYSTICK_DEVICE=/dev/input/js0 (a user can put this in /etc/environment and reboot to apply it everywhere).

 * rmmod evdev (quite likely to lose any unusual input devices you have).

 * Compile your own SDL with --disable-input-events

Possible fixes:

 * Compile SDL with --disable-input-events for everyone. This actually only affects the joystick driver, but breaks things for anyone who has a joystick that either only appears as an event device, or benefits from the "extra information about their hats or balls" that the SDL source mentions.

 * Tweak SDL_sysjoystick.c to prefer /dev/input/js0. Breaks things for anyone whose joystick needs the "extra information".

 * Best, in my opinion: extend the "special_joysticks" structure at the top of that file with a list of joystick names for which evdev should never be used, starting with "SAITEK CYBORG 3D USB".

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[EricDHH (ericdhh)]

Ubuntu 14.04 LTS AMD64

Same bug exist on, now upcoming steam games use evdev and there is no point to calibrate the joystick there.