qmk/qmk_firmware

[Bug] EXTRAKEY_ENABLE build flag is breaking steaminput on linux

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#25,277 opened on May 19, 2025

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bughelp wanted

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Description

Describe the Bug

If you build qmk with EXTRAKEY_ENABLE which is default your keyboard will report that is supporting every HID available which will break steaminput. https://github.com/qmk/qmk_firmware/blob/02517bd8069ea6d22a3b10945611b0170f7ef7d4/tmk_core/protocol/usb_descriptor.c#L344-L347

Steam and KDE system settings will also detect your keyboard as joystick / gamepad.

For example my dualshock 4 controller will stop working in Dark souls 2 if I connect QMK keyboard. For now I have moved back to stock firmware which doesn't have this issue.

Keyboard Used

gmmk/gmmk2/p96/iso:default

Link to product page (if applicable)

No response

Operating System

Linux, Opensuse Tumbleweed

qmk doctor Output

Is AutoHotKey / Karabiner installed

  • AutoHotKey (Windows)
  • Karabiner (macOS)

Other keyboard-related software installed

No response

Additional Context

Steam related bug https://github.com/ValveSoftware/steam-for-linux/issues/3384

And more context what is probably happening. This patch was for microsoft keyboard https://github.com/torvalds/linux/commit/1989dada7ce07848196991c9ebf25ff9c5f14d4e

Contributor guide

Research direction
Investigate the USB descriptor generation in tmk core/protocol/usb descriptor.c around line 344 where EXTRAKEY ENABLE causes the keyboard to report all HID usages. Review the Valve Software Steam bug report (issue #3384) and the Linux kernel commit that added a similar workaround for Microsoft keyboards. Consider implementing a conditional descriptor or a build flag to restrict reported HID usages when EXTRAKEY ENABLE is set.
Tech stack
cshell
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
C programmingUSB HID descriptorsQMK firmware build system
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35