"Controller disconnected every few seconds" (Forza Horizon, held steady): the
virtual UHID DualSense emitted HID report 0x01 ONLY on state change, but a real
DualSense streams it continuously (~250 Hz). When the player holds the
wheel/throttle steady the client sends no wire events, so the host wrote nothing
and /dev/uhid went silent for seconds — the kernel hid-playstation driver / Proton
/ SDL treat that as an unplugged controller. (The uinput X-Box pad is immune:
evdev holds last-known state with no periodic-report requirement.)
Add DualSenseManager::heartbeat(max_gap): re-emit each live pad's CURRENT report
when it's been silent for max_gap (idempotent — a stale-but-correct frame, never a
phantom input; write_state bumps seq+timestamp). write() resets the per-pad timer,
so an actively-used pad emits no extra reports — the heartbeat only fills genuine
silence. PadBackend::heartbeat() drives it at an 8 ms gap (~125 Hz) for DualSense
(no-op for X-Box), called every input-thread tick (the loop already runs ≤4 ms).
GET_REPORT feature replies + the pad lifecycle were ruled out by the investigation
(pad is created once, never torn down mid-session). Compiles, clippy/fmt clean, 78
host tests pass. Verify on the box: held-idle DualSense stays present in evtest /
no SDL CONTROLLERDEVICEREMOVED; Forza no longer toasts "controller disconnected".
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
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