Greenfield virtual Steam Deck controller, the Steam analogue of the shipped
virtual DualSense. Proves the kernel hid-steam driver binds a /dev/uhid
28DE:1205 device, registers it as a real Steam Deck, and parses our input
reports — the go/no-go gate for the full Steam Controller/Deck pipeline.
- inject/proto/steam_proto.rs: keeper module — the vendor HID descriptor (one
feature report, the sole thing steam_is_valve_interface() checks), the
command/feature IDs, serialize_deck_state, and the serial GET_REPORT reply.
Unit-tested.
- src/bin/steam_uhid_spike.rs: throwaway M0 spike (Linux-only) — opens
/dev/uhid, creates the device, services the handshake including
UHID_SET_REPORT (which the DualSense backend omits and which hid-steam
stalls ~5s/cmd without), and heartbeats a neutral report.
- design/steam-controller-deck-support.md: full design + M0–M7 plan; the two
walls (Steam Input capture ownership; virtual-Steam recognition) and the
fidelity ceiling. Status: M0 GREEN.
On-box (headless Ubuntu 26.04, kernel 7.0, no Steam): journalctl -k shows
hid-steam binding the device (rebind off hid-generic), "Steam Controller
connected", and the kernel creating BOTH a "Steam Deck" gamepad evdev and a
"Steam Deck Motion Sensors" IMU evdev (INPUT_PROP_ACCELEROMETER). A
layout-agnostic mash-probe drove 23 distinct BTN_* codes through
hid-steam -> evdev, proving the input-report parse path. M1 line-checks the
exact per-bit report layout against the lab kernel.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
