daedalus-v4l2

reauktion/daedalus-v4l2

Fork 0

Commit Graph

Author	SHA1	Message	Date
marfrit	895f57c63a	Phase 8.2: kernel ↔ daemon chardev bridge with round-trip test Adds /dev/daedalus-v4l2 misc chardev to the kernel module. The chardev is the IPC channel for the future userspace decoder daemon: kernel enqueues REQ_* messages, daemon read()s them, processes, write()s RESP_* back. Wire protocol (pre-1.0, header in include/daedalus_v4l2_proto.h): - struct daedalus_msg_hdr: magic (D04V) + version + type + cookie + payload_len + reserved - Request/response separated by high bit of type field - Max 64 KiB payload per message - Cookie correlates request with matching response Kernel implementation (kernel/daedalus_v4l2_chardev.{c,h}): - Single-instance chardev (-EBUSY on second open) - In-kernel FIFO bounded at 64 messages - Blocking + non-blocking read; poll() with EPOLLIN on queued - write() parses + validates header, logs response at pr_debug - Bad magic → -EBADMSG, bad version → -EPROTO, oversize → -EMSGSIZE - All error paths free resources Phase 8.2 test trigger via debugfs: - /sys/kernel/debug/daedalus_v4l2/test_ping — any byte enqueues a PING with a fixed 24-byte payload. Removed in Phase 8.4 when real REQ_DECODE from V4L2 path takes over. Userspace verification tool (tools/test_chardev_pingpong.c): - Real C program, proper error reporting via strerror - Validates the 6-step round-trip: open → empty-queue EAGAIN → trigger ping → read PING → verify all fields → write PONG → close - Builds with -Wall -Wextra clean Verification on hertz (Pi 5, 6.12.75+rpt-rpi-2712): $ sudo insmod daedalus_v4l2.ko $ sudo tools/test_chardev_pingpong opening /dev/daedalus-v4l2... non-blocking read on empty queue: EAGAIN ✓ injected PING via debugfs ✓ read PING: magic ✓ version ✓ type=PING ✓ cookie=0x1234 ✓ payload=24 bytes payload: "DAEDALUS-V4L2-PING-PL" wrote PONG (cookie=0x1234) ✓ ALL TESTS PASSED. $ sudo rmmod daedalus_v4l2 # clean Per correctness-before-speed: full kerneldoc on structs, 8-tab kernel style, SPDX headers, proper error paths, real test program (not "I ran it once"), failure-mode coverage documented. Phase 8.3 next: userspace daemon with dlopen'd FFmpeg parse path. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>	2026-05-18 15:05:54 +00:00
marfrit	9415b7e0f7	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>	2026-05-18 15:03:22 +00:00

Author

SHA1

Message

Date

marfrit

895f57c63a

Phase 8.2: kernel ↔ daemon chardev bridge with round-trip test

Adds /dev/daedalus-v4l2 misc chardev to the kernel module. The
chardev is the IPC channel for the future userspace decoder
daemon: kernel enqueues REQ_* messages, daemon read()s them,
processes, write()s RESP_* back.

Wire protocol (pre-1.0, header in include/daedalus_v4l2_proto.h):
- struct daedalus_msg_hdr: magic (D04V) + version + type +
  cookie + payload_len + reserved
- Request/response separated by high bit of type field
- Max 64 KiB payload per message
- Cookie correlates request with matching response

Kernel implementation (kernel/daedalus_v4l2_chardev.{c,h}):
- Single-instance chardev (-EBUSY on second open)
- In-kernel FIFO bounded at 64 messages
- Blocking + non-blocking read; poll() with EPOLLIN on queued
- write() parses + validates header, logs response at pr_debug
- Bad magic → -EBADMSG, bad version → -EPROTO, oversize → -EMSGSIZE
- All error paths free resources

Phase 8.2 test trigger via debugfs:
- /sys/kernel/debug/daedalus_v4l2/test_ping — any byte
  enqueues a PING with a fixed 24-byte payload. Removed in
  Phase 8.4 when real REQ_DECODE from V4L2 path takes over.

Userspace verification tool (tools/test_chardev_pingpong.c):
- Real C program, proper error reporting via strerror
- Validates the 6-step round-trip: open → empty-queue EAGAIN →
  trigger ping → read PING → verify all fields → write PONG → close
- Builds with -Wall -Wextra clean

Verification on hertz (Pi 5, 6.12.75+rpt-rpi-2712):
  $ sudo insmod daedalus_v4l2.ko
  $ sudo tools/test_chardev_pingpong
  opening /dev/daedalus-v4l2...
    non-blocking read on empty queue: EAGAIN ✓
    injected PING via debugfs ✓
    read PING: magic ✓ version ✓ type=PING ✓ cookie=0x1234 ✓ payload=24 bytes
      payload: "DAEDALUS-V4L2-PING-PL"
    wrote PONG (cookie=0x1234) ✓
  ALL TESTS PASSED.
  $ sudo rmmod daedalus_v4l2      # clean

Per correctness-before-speed: full kerneldoc on structs, 8-tab
kernel style, SPDX headers, proper error paths, real test
program (not "I ran it once"), failure-mode coverage documented.

Phase 8.3 next: userspace daemon with dlopen'd FFmpeg parse path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-18 15:05:54 +00:00

marfrit

9415b7e0f7

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>

2026-05-18 15:03:22 +00:00

2 Commits