qmk/qmk_firmware

[Bug] Mouse Reports are sent twice if shared EP is enabled

Open

#10,978 opened on Nov 19, 2020

View on GitHub
 (1 comment) (0 reactions) (0 assignees)C (20,368 stars) (43,867 forks)batch import
bughelp wanted

Description

Describe the Bug

If you use a tool like Spy++ on Windows, you can see it clearly, but when the shared EP stuff is enabled, the mouse reports are double sent. Which can be problematic for scrolling, for instance.

Disabling the shared endpoint fixes the issue outright, but on limited boards, that's not a good solution.

System Information

  • Keyboard: ErgoDox EZ, Moonlander
  • Operating system: Windows 10
  • AVR GCC version: 8.4
  • ARM GCC version: 8.3
  • QMK Firmware version: 0.10.50
  • Any keyboard related software installed?

Contributor guide

Tech stack
c
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.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
basic knowledge of USB HIDfamiliarity with QMK firmware structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate the shared endpoint (EP) logic in QMK's USB HID implementation. The relevant code is likely in tmk core/protocol/usb descriptor.c and tmk core/protocol/hid.c. Check how mouse reports are queued and sent when shared EP is enabled. Look for double send conditions by tracing the report transmission path. The issue mentions that disabling shared EP fixes it, so focus on the conditional logic that enables shared EP.