Phase 8.1: kernel V4L2 device skeleton (out-of-tree module)
Out-of-tree Linux kernel module registering /dev/videoNN. Phase
8.1 scope: skeleton only — VIDIOC_QUERYCAP works, no codec
ioctls / no vb2_queue / no controls yet.
Real V4L2 plumbing throughout per "correctness before speed":
platform_device + v4l2_device + video_device, properly nested
with error paths and devm_kzalloc-managed lifetime. Per-cycle 9
discipline ports to kernel code: SPDX header, kernel coding
style (8-tab, static-by-default), kerneldoc on structs, no
shortcuts.
Files (~250 LOC total):
- kernel/Makefile — out-of-tree kbuild with checkpatch target
- kernel/daedalus_v4l2_main.c — module init/exit + probe/remove
Verification on hertz (Pi 5, 6.12.75+rpt-rpi-2712):
- Builds clean with -Wall -Wextra. No warnings.
- modprobe / rmmod round-trip clean. No dmesg taints beyond
the expected "out-of-tree taint" line.
- v4l2-ctl --list-devices shows: "daedalus-fourier V3D7+NEON
(platform:daedalus_v4l2): /dev/video0"
- VIDIOC_QUERYCAP returns driver/card/bus/caps as specified.
- v4l2-compliance: 44/48 passing. The 4 failures are exactly
the format/buffer ioctls Phase 8.2 will implement
(ENUM_FMT, G_FMT, Scaling, REQBUFS) — not skeleton bugs,
legitimately-absent features.
Documentation: docs/phase_8_1_closure.md captures full
verification output + Phase 8.2 plan.
Phase 8.1 acceptance criteria met:
- ✓ /dev/videoNN appears via v4l2-ctl --list-devices
- ✓ VIDIOC_QUERYCAP responds with sensible values
- ✓ rmmod is clean (no kref leaks)
- ✓ v4l2-compliance passes except for explicit Phase 8.2 work
Next: Phase 8.2 chardev bridge for kernel ↔ daemon IPC.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
marfrit
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