Hi guys, I tried the udev rule from the debian package -> steam-device. I think that it's not complete to use correctly the gamepad.
With the actual udev rule, the controller is correctly recognized on Steam on Big Picture mode but in game like Metro 2033 / Last Light Redux, the controller is not recognized as a gamepad but still as a keyboard. If I add "OPTIONS+="static_node=uinput" to "# Steam Controller udev write access", the controller is recognized correctly as a gamepad in my games. thanks to correct the package :)