I am having a weird issue with steam controller on desktop in KDE Plasma. I am having this problem on 2 computers, though the issue presents slightly differently.
I have a dual boot AMD 3600X, with a 5700XT, 16gb ram, running latest stable Manjaro. When sitting at the computer and I turn on the Steam Controller (in dongle mode), the mouse cursor moves, but triggers do not fire a mouse click until a few minutes after connection. A weird quirk, but it isn’t broken (though I would like to get to the bottom of this).
I have a second computer, much more lightweight. Its an old Dell Optiplex 3010 that I’m connecting to over Steam Link app on an android tablet. The steam controller is connected to the tablet in this case (BLE), but I get the same issue: touchpad moves the mouse around just fine, but the triggers don’t fire clicks. However, in this computers case, the triggers never send clicks, even after an hour of connection.
I think the issues must be related, but the steam link layer is probably preventing whatever “fix” appears in the first computer. I just installed the game-devices-udev package through pacman but that has not had any effect on this issue. I also put an old udev rule inplace that used to be required on Ubuntu 15 or older, but that also had no effect.
EDIT: There appears to be more wrong with the Optiplex than I initially thought. I tried to test if the controller worked at all as a controller in a full screen game. While streaming, as soon as I launch a game it crashes sddm. If I’m not streaming (sitting at the computer) it doesn’t crash. This may have more to do with the weak processor and onboard video though.