VoodooI2CHID (macOS 26 fork)

Fork of VoodooI2CHID — the I2C-HID satellite for VoodooI2C. Used to bring up an ELAN0001 precision touchpad on a Lenovo Legion Y7000P IRH8 under macOS 26.

What changed

The upstream probe is fragile: a single failed HID descriptor read dooms the whole boot, and in polling mode an interrupt event source can be registered that never fires.

Change	Why
HID descriptor read retried (~1 s total)	Some devices need time after _PS0 / reset before answering
Fallback to register 0x0001 when the HIDG _DSM is missing	HID-over-I2C always exposes the descriptor at 0x0001
Explicit timer polling when VoodooI2C reports Interrupt Mode = Polling	An interrupt source that registers but never fires leaves the device silent
Host-initiated reset no longer blocks the work loop for 12 s in polling mode	The polling timer lives on that work loop and could not run
Report descriptor read retried (5 × 100 ms)	Same readiness problem as above
Allocation and return-value checks in report paths	Avoid null dereferences under memory pressure
Division-by-zero guards when parsing contact counts	Malformed descriptors could panic the kernel
PTP mode switch written twice + logged	Some firmwares ignore the first switch request
More diagnostics	HID descriptor contents, element counts, interrupt mode

The changes are limited to robustness; the HID protocol implementation is unchanged.

Installation

Install together with the core:

VoodooI2C.kext/Contents/PlugIns/VoodooI2CServices.kext
VoodooI2C.kext/Contents/PlugIns/VoodooGPIO.kext
VoodooI2C.kext/Contents/PlugIns/VoodooInput.kext
VoodooI2C.kext
VoodooI2CHID.kext

VoodooI2CHID.kext must be listed in config.plist → Kernel → Add — the core alone produces no touchpad.

Building

xcodebuild -project VoodooI2CHID.xcodeproj -scheme VoodooI2CHID \
           -configuration Release CODE_SIGNING_ALLOWED=NO

The project expects MacKernelSDK next to it (CI checks it out), same as upstream.

Diagnostics

ioreg -c VoodooI2CHIDDevice -l | head -40
log show --last boot --debug --predicate 'eventMessage CONTAINS "VoodooI2CHID"' | tail -40

Look for:

HID descriptor: VID 0x04f3 PID … report descriptor … bytes
Multitouch elements: N finger collection(s) … input mode yes
Device switched to Precision Touchpad mode

Credits

• Alexandre Daoud / coolstar — original VoodooI2CHID
• kprinssu, 1Revenger1 — upstream maintenance
• acidanthera — MacKernelSDK, VoodooInput

License

GPL-3.0, inherited from VoodooI2C.