• Steam client version: 1482202200, steam 1.0.0.54-1, steam-devices 1.0.0.54-1
• Distribution (e.g. Ubuntu): Debian unstable
• Opted into Steam client beta?: no
• Have you checked for system updates?: yes

This is Debian bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=818905.

/dev/uinput does not receive non-trivial ACLs, and as a result Steam's Steam Controller support cannot synthesize gamepad input events for games that expect an X-Box-style controller (specifically, I'm testing with Shadow Tactics: Blades of the Shogun in Big Picture mode).

Expected:

$ getfacl /dev/uinput
getfacl: Removing leading '/' from absolute path names
# file: dev/uinput
# owner: root
# group: root
user::rw-
user:somebody:rw-
group::---
mask::rw-
other::---

where somebody is whichever user is logged in on the currently active virtual console.

Actual:

$ getfacl /dev/uinput
getfacl: Removing leading '/' from absolute path names
# file: dev/uinput
# owner: root
# group: root
user::rw-
group::---
other::---

Suggested solution

A change to the udev rules seems to resolve the issue: replace Valve's current recommendation

KERNEL=="uinput", SUBSYSTEM=="misc", TAG+="uaccess"

with

KERNEL=="uinput", SUBSYSTEM=="misc", TAG+="uaccess", OPTIONS+="static_node=uinput"