# Linux Kernel Bug Report: Intel Lunar Lake Communication Controller Driver Missing

## **Hardware Information**
- **System:** HP OmniBook 14-fm0013dx (Intel Lunar Lake)
- **CPU:** Intel Core Ultra 5 226V (Lunar Lake)
- **Kernel:** 6.15.9-201.fc42.x86_64
- **Distribution:** Fedora 42
- **BIOS:** Insyde F.06 04/21/2025

## **Problem Description**
Intel Lunar Lake communication controller `8086:a862` fails to initialize with invalid IRQ assignment (IRQ 255), preventing accelerometer/gyroscope sensors from working. This results in non-functional automatic screen rotation on 2-in-1 convertible laptops.

This affects HP OmniBook X Flip series with Intel Lunar Lake processors. Similar issues likely exist on other Lunar Lake 2-in-1 laptops requiring accelerometer functionality.

https://linux-hardware.org/?id=pci:8086-a862-103c-8d9f

## **Device Details**
```
00:13.0 Communication controller [0780]: Intel Corporation Device [8086:a862] (rev 10)
	Subsystem: Hewlett-Packard Company Device [103c:8d9f]
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 255
	IOMMU group: 8
	Region 0: Memory at 2813324000 (64-bit, non-prefetchable) [size=4K]
```

**Key Issue:** `Interrupt: pin A routed to IRQ 255` (invalid IRQ assignment)

## **Expected vs Actual Behavior**
**Expected:** Device should receive valid IRQ and expose IIO sensors for accelerometer/gyroscope  
**Actual:** Device fails to initialize due to IRQ 255, no IIO devices created

## **Impact**
- ✅ Tablet mode detection works (Intel HID switches at `00:12.0`)
- ❌ Automatic screen rotation fails (no accelerometer data)
- ❌ `iio-sensor-proxy` service cannot start (no IIO devices)

## **Evidence**

### **Hardware Probe**
Complete hardware information: https://linux-hardware.org/?probe=c2a2d095f7

### **Working Intel Sensor Hub (Comparison)**
```
00:12.0 Communication controller [0780]: Intel Corporation Lunar Lake-M Integrated Sensor Hub [8086:a845] (rev 10)
	Interrupt: pin A routed to IRQ 145
	Kernel driver in use: intel_ish_ipc
```

### **ACPI Errors Related to Sensors**
```
[    0.115343] ACPI BIOS Error (bug): Could not resolve symbol [\_SB.PC00.I2C3.TPD0], AE_NOT_FOUND
[    0.115581] ACPI BIOS Error (bug): Could not resolve symbol [\_SB.PC00.I2C5.TPL1], AE_NOT_FOUND
```

### **Missing IIO Subsystem**
```
$ ls /sys/bus/iio/devices/
ls: cannot access '/sys/bus/iio/devices/': No such file or directory
```

### **iio-sensor-proxy Failure**
```
$ systemctl status iio-sensor-proxy
○ iio-sensor-proxy.service - IIO Sensor Proxy service
     Active: inactive (dead)

Aug 13 22:21:45 fedora iio-sensor-prox[5826]: Invalid bitmask entry for /sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/event1
```

### **Driver Support Check**
Device `8086:a862` is not listed in `intel_ish_ipc` driver aliases:
```
$ modinfo intel_ish_ipc | grep alias | grep -E "(a845|a862)"
alias:          pci:v00008086d0000A845sv*sd*bc*sc*i*
# No a862 entry found
```

## **Workaround**
None available. Screen rotation must be done manually via `xrandr`.

## **Related Devices Working**
- Intel Arc Graphics 130V: ✅ Working (`xe` driver)
- Wi-Fi 6E AX231: ✅ Working (`iwlwifi`)
- Audio (Lunar Lake-M HD): ✅ Working (`sof_audio_pci_intel_lnl`)
- Bluetooth: ✅ Working (after linux-firmware 20241110+)
- Intel HID switches: ✅ Working (tablet mode detection)

## **Suggested Fix**
Add device ID `8086:a862` to appropriate Intel sensor hub driver (likely `intel_ish_ipc`) and resolve ACPI IRQ assignment issue for Lunar Lake communication controllers.

Reproducible: Always