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6f4b580f7c8d4c6705de26318fea3e111d08ce97
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Author SHA1 Message Date
marfrit 6f4b580f7c Phase 8.5: full V4L2 m2m driver, VP9 decode via QBUF/DQBUF 
Replaces the Phase 8.4 debugfs-triggered chardev path with a
real V4L2 m2m driver. Userspace clients now drive decoding the
standard way — S_FMT / REQBUFS / QBUF on the OUTPUT (bitstream)
queue, DQBUF on the CAPTURE (NV12M) queue. Kernel device_run
packs the bitstream into REQ_DECODE; daemon decodes via FFmpeg;
RESP_FRAME's inline NV12 pixel payload lands in the CAPTURE
buffer. Phase 8.6 swaps the inline payload for dmabuf so big
frames stop being capped at 64 KiB.

Kernel (daedalus_v4l2_main.c, rewritten + main.h added):
- Per-open struct daedalus_ctx: v4l2_fh, m2m_ctx, ctrl_handler,
  per-queue v4l2_pix_format_mplane.
- Two vb2_queues (vb2_vmalloc_memops for both — no DMA needed
  yet; 8.6 switches CAPTURE to dma_contig for dmabuf-export):
    OUTPUT  = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE,  VP9_FRAME
    CAPTURE = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE, NV12M
- Full v4l2_ioctl_ops table: querycap, enum_fmt, g/s/try_fmt
  for both queues, reqbufs/querybuf/qbuf/dqbuf/create_bufs/
  prepare_buf/expbuf/streamon/streamoff via v4l2_m2m_ioctl_*
  helpers.
- v4l2_m2m_ops.device_run: peeks next OUTPUT buf, builds
  REQ_DECODE inline with the bitstream bytes, enqueues with an
  auto-incrementing cookie, stores {ctx, src_buf, dst_buf} in
  a per-device inflight list. Job stays open until RESP_FRAME.
- daedalus_complete_resp_frame(): pops the inflight entry,
  memcpys inline NV12 pixels into the CAPTURE buffer (Y plane
  + interleaved CbCr), finishes via
  v4l2_m2m_buf_done_and_job_finish — NOT plain buf_done +
  job_finish, which leaves the src buf on the m2m queue and
  causes device_run to immediately re-run on the same input
  (caught on first run; second REQ_DECODE for same bitstream +
  eventual oops in stop_streaming on teardown).

Kernel (daedalus_v4l2_chardev.c):
- RESP_FRAME handler now hands inline pixel payload to
  daedalus_complete_resp_frame so it lands in the CAPTURE
  vb2 buffer. Existing PONG and debugfs test_decode paths still
  work; the latter produces a harmless ratelimited "unknown
  cookie" since it bypasses V4L2 m2m.

Daemon (decoder.c, decoder.h):
- daedalus_decoder_run_request signature extended with
  (nv12_out, nv12_cap, nv12_used). After the FNV-1a digest the
  decoder packs YUV420P into NV12 in the caller's buffer: Y
  plane line-by-line stripped of stride padding; Cb/Cr
  interleaved into a single chroma plane. Truncation silent —
  kernel only memcpys what fits in the CAPTURE plane.

Daemon (chardev_client.c):
- handle_req_decode allocates a response buffer sized for the
  full chardev payload, lets decoder fill the pixel area
  after the resp_frame struct, sends the full payload via the
  existing send_response.

Test client (tools/test_m2m_decode.c, new):
- Minimal V4L2 m2m client: S_FMT both queues, REQBUFS 1 each,
  mmap+fill OUTPUT, QBUF both, STREAMON, poll, DQBUF, dump
  CAPTURE planes to a raw NV12 file. ~250 LOC; verifies the
  whole flow without needing v4l2-ctl framing.

Roadmap update (docs/roadmap.md):
- Phase 8.4 retitled "daemon ↔ kernel decode round-trip"
  to reflect what actually shipped (vs. the original V4L2-
  ioctl-driven plan which moved here).
- Phase 8.5 retitled "full V4L2 m2m driver" with closure
  status.
- Phase 8.6 reshaped to two tracks: dmabuf + AV1/H.264/
  stateless controls + media controller. Adds the punch list
  of v4l2-compliance failures (DECODER_CMD, S_FMT colorspace)
  that 8.6 will fix.

Verification on hertz (Pi 5, 6.12.75+rpt-rpi-2712):

  Kernel + daemon build clean (-Wall -Wextra clean both sides).
  Test harness drives one VP9 keyframe end-to-end:
    OUTPUT REQBUFS -> 2
    CAPTURE REQBUFS -> 2
    QBUF OUTPUT[0] bytesused=1566
    QBUF CAPTURE[0]; STREAMON both
    poll revents=0x5
    DQBUF OUTPUT[0] flags=0x4001 (DONE)
    DQBUF CAPTURE[0] flags=0x4000 payloads=[12288, 6144]
    wrote 12288 Y + 6144 UV bytes to /tmp/out_m2m.nv12

  Pixel correctness vs reference:
    ffmpeg -i vp9_small.ivf -pix_fmt nv12 -f rawvideo -y ref.nv12
    cmp /tmp/out_m2m.nv12 /tmp/ref.nv12 → match ✓
  Byte-for-byte identical to FFmpeg's stock CPU decode.

  v4l2-compliance: detected as Stateless Decoder; most ioctls
  pass; two expected fails documented in closure doc
  (DECODER_CMD/media controller, S_FMT colorspace).

  Clean teardown: SIGTERM the daemon, rmmod the module, no
  oops/WARN in dmesg.

Per correctness-before-speed:
- Real V4L2 ioctl table (not stubs); uses v4l2-core helpers
  where they exist instead of reinventing.
- v4l2_m2m_buf_done_and_job_finish (not the manual sequence)
  to keep scheduler state consistent.
- Bit-exact reference comparison, not just "looks right."
- Documented every compliance failure with the planned fix.
- All resource paths (kmalloc/kfree, inflight list cleanup,
  src/dst buf removal in stop_streaming) handled on every
  error branch.

Phase 8.6 next: dmabuf-export for CAPTURE (removes 64 KiB
frame-size cap), add AV1+H.264 codecs, add V4L2 stateless
controls + media controller binding, fix the colorspace +
cookie-namespace compliance issues.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
 2026-05-18 15:55:10 +00:00
marfrit 2a449632b9 Phase 8.4: daemon ↔ kernel decode round-trip (VP9 end-to-end) 
Wires the Phase 8.3 FFmpeg loader through the Phase 8.2 chardev
bridge: kernel injects REQ_DECODE carrying a raw VP9 access unit,
daemon hands the bitstream to libavcodec via dlopen, sends
RESP_FRAME back with a content-dependent FNV-1a digest of the
decoded YUV planes. Pure CPU decode for now — Phase 8.5 swaps in
dmabuf + QPU dispatch.

Protocol (include/daedalus_v4l2_proto.h):
- New REQ_DECODE (kernel→daemon) and RESP_FRAME (daemon→kernel)
  message types, with fixed-size payload structs.
- New DAEDALUS_CODEC_VP9/AV1/H264 enum (wire-stable so 8.6's
  AV1+H.264 work doesn't move existing values).
- New DAEDALUS_DECODE_* status enum (OK / NO_FRAME / ERR_OPEN /
  ERR_SEND / ERR_RECV / ERR_CODEC).
- Converted the prior `enum daedalus_msg_type` to #defines —
  high-bit values exceed INT_MAX and tripped -Wpedantic on
  userspace; kernel uABI headers use the same idiom.

Kernel (kernel/daedalus_v4l2_chardev.c):
- New debugfs entry /sys/kernel/debug/daedalus_v4l2/test_decode:
  writing raw bitstream bytes wraps them in a REQ_DECODE
  (codec=VP9 for Phase 8.4) and enqueues with an
  auto-incrementing cookie.
- daedalus_chardev_write learned RESP_FRAME: parses the payload
  and emits a single pr_info line with decode metadata. Keeps
  existing PONG handling on the default arm.

Daemon (daemon/src/...):
- chardev_client.{c,h} — opens /dev/daedalus-v4l2, blocking read
  loop, single-buffer write() responses (kernel chardev has only
  .write, not .write_iter, so writev lands as -EINVAL —
  discovered the hard way during first run).
- decoder.{c,h} — lazily-opened AVCodecContext per codec, shared
  AVPacket/AVFrame pair, descriptor-driven plane walker
  (av_pix_fmt_desc_get) so the same hash path covers YUV420P,
  YUV422P, YUV444P, GBRP and other 8-bit planar layouts.
  Generalised after first run decoded testsrc as GBRP (71)
  rather than the assumed YUV420P.
- `daemon` command in main.c opens the chardev and runs the loop
  until SIGINT/SIGTERM. Cookie correlation handled end-to-end.
- ffmpeg_loader gained av_pix_fmt_desc_get (23 symbols total).

Build:
- CMakeLists adds chardev_client.c + decoder.c; explicit
  -I../include for the shared protocol header.
- Still -Wall -Wextra -Wpedantic clean.

Verification on hertz (Pi 5, 6.12.75+rpt-rpi-2712):

  $ ffmpeg ... -pix_fmt yuv420p -c:v libvpx-vp9 -frames:v 1 \
           -y /tmp/vp9_test.ivf
  $ python3 ... strip IVF framing → vp9_keyframe.bin (3268 B)

  $ sudo insmod kernel/daedalus_v4l2.ko
  $ daedalus_v4l2_daemon -v daemon &
  $ sudo dd if=vp9_keyframe.bin \
         of=/sys/kernel/debug/daedalus_v4l2/test_decode

  daemon: REQ_DECODE cookie=2 → decoded yuv420p 320x240
          fnv1a=0x6ef10d71 luma=76800 chroma=38400
  kernel: RESP_FRAME cookie=2 status=0 320x240 pixfmt=0
          fnv1a=0x6ef10d71  ← matches daemon ✓

Hash properties verified:
  cookie=2  testsrc 3268 B → 0x6ef10d71  (first decode)
  cookie=3  red     44 B   → 0x7f6e5dc5  (content-dependent ✓)
  cookie=4  testsrc 3268 B → 0x6ef10d71  (deterministic ✓)
  cookie=5  64 B random    → status=101  (ERR_SEND, daemon alive)

Daemon survives bad input (FFmpeg "Invalid sync code" wrapped
into structured ERR_SEND response). Clean SIGTERM shutdown,
clean rmmod.

Phase 8.4 acceptance criteria met:
- ✓ end-to-end kernel→daemon→FFmpeg→kernel round-trip
- ✓ cookie correlation per request/response pair
- ✓ content-dependent + deterministic digest
- ✓ structured error responses (no daemon crash on bad input)
- ✓ clean teardown (SIGTERM + rmmod)
- ✓ builds clean on both kernel kbuild and daemon CMake

Per correctness-before-speed:
- Real chardev I/O (no shortcuts, no select-loop hacks)
- Real FFmpeg AVCodecContext lifecycle (lazily opened, properly
  freed on cleanup)
- Descriptor-driven plane walk (generalises across pix_fmts)
- Structured error path (not just log-and-continue)
- All resource paths cleaned up on every error branch
- Documented why FNV-1a digest, why write() not writev(), why
  pix_desc walk in docs/phase_8_4_closure.md

Phase 8.5 next: V4L2 m2m queue submits REQ_DECODE from
vidioc_qbuf; dmabuf carries actual pixel data so the chardev's
64 KiB cap doesn't gate frame size; begin substituting
daedalus_dispatch_* into the daemon's decode path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
 2026-05-18 15:22:16 +00:00
marfrit 873a04c622 Phase 8.3: userspace daemon scaffold + FFmpeg dlopen + parse path 
Builds the daemon executable per the locked Phase 8 architecture
(Option γ: dlopen FFmpeg at runtime). Phase 8.3 scope: parse
path validation only — no V4L2 wiring, no decode, no chardev
connection.

Components:
- daemon/CMakeLists.txt — CMake with -Wall -Wextra -Wpedantic
  clean. pkg-config for FFmpeg headers; only -ldl + -lpthread
  at link time.
- daemon/src/main.c — entry point, signal handlers
  (SIGINT/SIGTERM), command dispatcher. Currently `parse <file>`.
- daemon/src/ffmpeg_loader.{c,h} — runtime FFmpeg loader.
  dlopens libavformat.so.61, libavcodec.so.61, libavutil.so.59.
  Resolves 22 function pointers using POSIX-recommended
  *(void**)& dlsym idiom (per POSIX.1-2017 dlsym(3p) Rationale).
- daemon/src/parser.{c,h} — demux loop via avformat_open_input +
  av_read_frame. Per-frame logging on -v.
- daemon/src/log.{c,h} — logging facade (stderr Phase 8.3;
  syslog/journal planned for 8.5+).

Verification on hertz:
  $ ffmpeg -f lavfi -i testsrc=duration=2:size=320x240:rate=30 \
           -c:v libvpx-vp9 -y /tmp/testsrc.ivf
  $ daedalus_v4l2_daemon parse /tmp/testsrc.ivf
  [INFO] FFmpeg loaded: 7.1.3-0+deb13u1+rpt1 (libavformat 61.7.100)
  [INFO] video stream #0: codec=vp9 (Google VP9) 320x240, 0/0 fps
  [INFO] parse complete: 60 frames (1 key) total 17859 bytes

Error paths verified:
- Missing file → "avformat_open_input(...): code -2", exit 1
- No command → usage message, exit 2
- Bad command → usage message, exit 2

Per correctness-before-speed:
- Real CMake (no Makefile hacks)
- pkg-config for headers
- POSIX-conformant dlsym pattern (no -Wpedantic suppression)
- Real signal handling + proper exit codes
- Real logging with timestamp + level
- Headers included at compile-time for type safety; dlopen
  decouples runtime
- All FFmpeg resources freed on every exit path
- Builds clean on -Wall -Wextra -Wpedantic

Phase 8.3 acceptance criteria met:
- ✓ daemon binary builds
- ✓ dlopen FFmpeg at runtime
- ✓ demux a VP9 IVF file end-to-end
- ✓ per-frame metadata logged correctly
- ✓ frame count + keyframe count + byte total accurate

Phase 8.4 next: wire daemon to /dev/daedalus-v4l2 chardev,
add REQ_DECODE / RESP_FRAME handling, drive VP9 decode
end-to-end via daedalus_dispatch_* from daedalus-fourier.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
 2026-05-18 15:10:22 +00:00
marfrit c7d8050cc9 Initial scaffold: daedalus-v4l2 sibling repo 
V4L2 stateless decoder for Pi 5, backed by sibling
daedalus-fourier kernel library (VP9 + AV1 CDEF + H.264 video
decode kernels on VideoCore VII compute + ARM NEON).

Architecture locked 2026-05-18 by mfritsche per
daedalus-fourier/docs/phase8_scoping.md:
- Option B: Linux kernel V4L2 shim + userspace daemon (not
  v4l2loopback). Real /dev/videoNN; proper DRM PRIME for
  browser zero-copy.
- Option γ: dlopen FFmpeg at runtime as parser. No vendoring;
  fastest to v1.
- Sibling repo (this repo): V4L2-side work outside of
  daedalus-fourier so kernel-library API stays clean.

Components:
  kernel/ - Linux out-of-tree kernel module (GPLv2; V4L2
    device + chardev bridge to userspace daemon)
  daemon/ - userspace decoder daemon (BSD-2-Clause; links
    libdaedalus_core.a from sibling; dlopens FFmpeg)
  docs/   - architecture + 7-phase roadmap (8.1..8.7)
  include/ - shared headers between kernel and daemon

Roadmap (7 sub-phases, ~1 week each):
  8.1 kernel skeleton (/dev/videoNN with no-op ioctls)
  8.2 chardev bridge (kernel ↔ daemon ping-pong)
  8.3 daemon FFmpeg dlopen + parse path
  8.4 VP9 end-to-end via daedalus_dispatch_*
  8.5 dmabuf / DRM PRIME for zero-copy
  8.6 AV1 + H.264 codec support
  8.7 performance: hit 30fps@1080p (project floor)

No code yet — only README + design docs + directory structure.
First implementation work starts in Phase 8.1 next session.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
 2026-05-18 14:54:56 +00:00