You will need to update your udev rules for the Steam Controller

Valve have changed the USB/Bluetooth communication the Steam Controller uses, so on Linux you will need to update your udev rules.

Note: This is for the Beta client, but works on the stable client too. Even if you're on the stable client, it's likely a good idea to do it now ready for the next stable release on the Steam client.

See their announcement here, which links to this guide of issues.

Funnily enough, Valve didn't even list the actual file you need to update, so here it is:
/lib/udev/rules.d/99-steam-controller-perms.rules

You can open it easily doing this in terminal (on Ubuntu for example):
sudo gedit /lib/udev/rules.d/99-steam-controller-perms.rules

Edit it to look like this (make sure you edit the group name like it says!):

Quote# This rule is needed for basic functionality of the controller in Steam and keyboard/mouse emulation
SUBSYSTEM=="usb", ATTRS{idVendor}=="28de", MODE="0666"

# This rule is necessary for gamepad emulation; make sure you replace 'pgriffais' with a group that the user that runs Steam belongs to
KERNEL=="uinput", MODE="0660", GROUP="pgriffais", OPTIONS+="static_node=uinput"

# DualShock 4 wired
SUBSYSTEM=="usb", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="05c4", MODE="0666"
# DualShock 4 wireless adapter
SUBSYSTEM=="usb", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="0ba0", MODE="0666"
# DualShock 4 slim wired
SUBSYSTEM=="usb", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="09cc", MODE="0666"

# Valve HID devices over USB hidraw
KERNEL=="hidraw*", ATTRS{idVendor}=="28de", MODE="0666"

# Valve HID devices over bluetooth hidraw
KERNEL=="hidraw*", KERNELS=="*28DE:*", MODE="0666"

# DualShock 4 over bluetooth hidraw
KERNEL=="hidraw*", KERNELS=="*054C:05C4*", MODE="0666"

# DualShock 4 Slim over bluetooth hidraw
KERNEL=="hidraw*", KERNELS=="*054C:09CC*", MODE="0666"

I tried reloading udev rules after, but it didn't seem to work. A reboot with the new rules in place and it works once again.

Valve still haven't fixed the issue of the Steam Controller not working in wireless unless Steam is open though, bug reported here on September 1st. Not everyone seems to have that issue though.

Thanks to Furball in our Telegram group chat for pointing it out. Article taken from GamingOnLinux.com.