Public bug reported:

# Ubuntu Bug Report: IPU6 Camera Regression on ThinkPad X1 Carbon Gen 11

## Summary
Intel IPU6 MIPI camera completely non-functional on Ubuntu 25.10 beta (kernel 
6.17.0-4-generic) with ThinkPad X1 Carbon Gen 11, despite working in Ubuntu 
24.10. This represents a significant regression affecting Ubuntu-certified 
hardware.

## System Information
- **Hardware**: Lenovo ThinkPad X1 Carbon Gen 11 (Ubuntu certified)
- **Ubuntu Version**: Ubuntu 25.10 "Questing Quokka" (development branch)
- **Kernel**: 6.17.0-4-generic
- **IPU6 Hardware**: Intel Corporation Raptor Lake IPU [8086:a75d] (rev 01)
- **Sensor**: INT3474:01 (OV2740)

## Issue Details
- **Current Status**: Ubuntu 25.10 beta - complete camera failure
- **Related Reports**: Other users report regression from Ubuntu 24.10 
(working) to 25.04+ (broken)
- **Root Cause**: libcamera SimplePipeline enumeration failure + media 
controller link configuration errors

## Detailed Error Analysis

### libcamera Status
```
$ cam -l
[libcamera v0.5.0] INFO SimplePipeline simple.cpp:1695 No sensor found for 
/dev/media0
Available cameras: (none)
```

### Media Controller Errors
When attempting camera access via icamerasrc:
```
[CamHAL][ERR] setup Link ov2740 [-1:0] ==> Intel IPU6 CSI-2 [-1x0] enable 1 
failed.
[CamHAL][ERR] set MediaCtlConf McLink failed: ret = -1
[CamHAL][ERR] set up mediaCtl failed
[CamHAL][ERR] @configure Device Configure failed
```

### Hardware Detection (Working)
```
$ sudo dmesg | grep intel-ipu6
intel-ipu6 0000:00:05.0: Found supported sensor INT3474:01
intel-ipu6 0000:00:05.0: Connected 1 cameras
intel-ipu6 0000:00:05.0: CSE authenticate_run done
intel-ipu6 0000:00:05.0: IPU6-v3[a75d] hardware version 5
```

### Installed Packages (Complete)
All Intel camera packages properly installed from Lenovo OEM repository:
- libcamhal0 ✓
- gstreamer1.0-icamera ✓  
- libgsticamerainterface-1.0-1 ✓
- All libia-* and libgcss-* libraries ✓

## Attempted Solutions (All Failed)
1. **libcamera direct access**: SimplePipeline cannot enumerate sensor
2. **icamerasrc with device-name=ov2740-uf**: Media controller link setup fails
3. **v4l2loopback bridge**: Source pipeline fails before reaching bridge
4. **Manual media controller configuration**: Topology incomplete
5. **Lenovo OEM packages**: All installed, issue persists

## Impact Assessment
- **Severity**: High - Complete camera loss on certified hardware
- **Affected Users**: Multiple users confirmed on Launchpad bug #2107304
- **Workaround**: None functional (requires external USB webcam)

## Evidence of Broader Regression
This appears to be part of a broader regression pattern documented in other bug 
reports:
- Launchpad #2107304: "Intel MIPI Camera not working out of the box on 25.04 
where it did on 24.10"
- Launchpad #2114878: "ipu6 webcam not working in 25.04, was working in 24.04"
- Multiple users report cameras that worked in Ubuntu 24.10 stopped working in 
25.04+

## Technical Root Cause
The regression appears to be in the integration between:
1. **Kernel IPU6 drivers** (working - hardware detected)
2. **libcamera SimplePipeline** (broken - cannot enumerate sensors)  
3. **Media controller subsystem** (broken - link configuration fails)

The media controller topology shows IPU6 CSI receiver but missing sensor
enumeration, preventing proper pipeline establishment.

## Diagnostic Output
```
=== IPU6 Camera Diagnostic Results ===
✓ IPU6 Hardware detected: Intel Corporation Raptor Lake IPU [8086:a75d]
✓ Sensor detected in kernel: INT3474:01  
✓ All kernel modules loaded: intel_ipu6, intel_ipu6_isys, v4l2loopback
✓ All Intel packages installed: libcamhal0, gstreamer1.0-icamera, etc.
✓ PipeWire service running
✗ libcamera cannot enumerate cameras (SimplePipeline regression)
✗ OV2740 sensor not found in media topology  
✗ Media controller link configuration fails
✗ icamerasrc crashes with SIGSEGV during hardware access
```

## Expected Behavior
Camera should work out-of-the-box as it did in Ubuntu 24.10, given this is 
Ubuntu-certified hardware.

## Proposed Fix Priority
**Critical** - This affects Ubuntu-certified hardware and represents a clear 
regression from working functionality. The issue impacts the core camera 
subsystem integration rather than edge-case configuration problems.

## Additional Context
- Hardware certification: https://ubuntu.com/certified/202301-31165
- Related upstream issues: Multiple vendors affected (Dell, HP, Lenovo)
- Timeline: Regression introduced in 25.04 development cycle, persists in 25.10 
beta

## Reproduction Steps
1. Install Ubuntu 25.10 beta on ThinkPad X1 Carbon Gen 11
2. Install Intel camera packages: `sudo apt install libcamhal0 
gstreamer1.0-icamera`
3. Test camera: `cam -l` (shows no cameras)
4. Test browser: No functional camera in Firefox/Chrome
5. Check errors: Media controller link setup failures in journalctl

This regression needs attention before Ubuntu 25.10 final release to
restore functionality on certified hardware.

** Affects: libcamera (Ubuntu)
     Importance: Undecided
         Status: New

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Title:
  Ubuntu Bug Report: IPU6 Camera Regression on ThinkPad X1 Carbon Gen 11

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