fresnel-fourier

TL;DR

Peer campaign to libva-multiplanar, targeting fresnel (Pinebook Pro / Rockchip RK3399) instead of ohm (PineTab2 / RK3566). Same deliverable shape — make libva-v4l2-request-fourier work end-to-end, for production VA-API consumers — but on a different SoC with a different (and broader) V4L2 decoder surface.

The libva backend fork itself (libva-v4l2-request-fourier) is shared: it lives at ../libva-multiplanar/libva-v4l2-request-fourier/. This campaign does not nest a second copy. Code-side work that turns out to be RK3399-specific lands either as #ifdef/runtime-detected paths inside that fork's master or, if scope diverges sharply, on a feature branch — Phase 2 source-read of each iteration decides.

Origin

libva-multiplanar reached iter5-close on 2026-05-05 with the ohm path solid: hantro (rk3568-vpu DT compatible) decodes H.264 to NV12 dmabufs end-to-end, three iterations of bugs fixed, mpv --hwdec=vaapi smooth, firefox-fourier RDD-sandboxed Firefox engages the backend without MOZ_DISABLE_RDD_SANDBOX=1, chromium-fourier 149 confirmed as the regression-check consumer.

That campaign's README explicitly names fresnel (RK3399) and ampere/boltzmann (RK3588) as "future iterations after ohm path is solid" (libva-multiplanar/README.md:87). fresnel-fourier is the formal peer campaign for the RK3399 leg of that promise.

Topology choice (LOCKED 2026-05-07): peer campaign, not child of libva-multiplanar. Each runs its own 8(+1) phase loop. Cross-link only — fresnel-fourier results do not gate libva-multiplanar's Phase 8 close (which already happened iteration-by-iteration on ohm).

Hardware target

fresnel — Pinebook Pro laptop. See reference_fresnel_kernel_constraints.md for the custom-OC-kernel discipline (don't let pacman -Syu clobber the OC DTB) and project_fresnel.md for fleet placement.

Property	Value
SoC	Rockchip RK3399 (2× Cortex-A72 + 4× Cortex-A53)
GPU	Mali-T860 MP4 (Midgard, panfrost)
Decoder block 1	rkvdec (/dev/video3) — H.264 + HEVC + VP9
Decoder block 2	hantro-vpu-dec (rk3399-vpu-dec, /dev/video5) — MPEG-2 + VP8 (RK3399 hantro does not advertise H.264; corrected 2026-05-07 from empirical V4L2 enumeration — see phase0_evidence/2026-05-07/v4l2_inventory_findings.md)
Encoder block	hantro-vpu-enc (/dev/video4) — JPEG only
OS	EndeavourOS-ARM (Arch derivative; same pacman + marfrit-packages mechanism as ohm)
Kernel	linux-eos-arm 6.19.9-99 — CONFIG_FTRACE=y, CONFIG_FUNCTION_TRACER=y, CONFIG_DYNAMIC_FTRACE=y, CONFIG_TRACING=y verified 2026-05-07. No rebuild needed for trace work.

The decode-side surface area is genuinely broader than ohm. ohm has hantro (H.264 + MPEG-2 + VP8) and an rkvdec block whose mainline rkvdec2/vdpu346 driver isn't merged. fresnel has hantro (MPEG-2 + VP8 only — empirical, see correction note in the table above) plus a fully-driven mainline rkvdec covering H.264 + HEVC + VP9. So this campaign exercises codecs (HEVC, VP9) the libva-v4l2-request-fourier fork has never run on real hardware to date, and there is exactly one decoder bind for H.264 (rkvdec) — no two-block routing decision.

GPU side: panfrost on Mali-T860 (Midgard) is a different generation than ohm's Mali-G52 (Bifrost). KWin / Mesa / panfrost stack regressions or wins on T860 are not assumed to track G52 — the kwin-fourier verdict from fourier_attribution doesn't transfer for free.

Scope (LOCKED 2026-05-07 in phase0_findings.md)

In scope:

• libva-v4l2-request-fourier backend exercised on fresnel V4L2 decode nodes (rkvdec + hantro-vpu-dec).
• Codecs: everything decode-capable — H.264 + HEVC + VP9 (via rkvdec) + MPEG-2 + VP8 (via hantro-vpu-dec). This is the explicit broadening from libva-multiplanar's H.264-first locked scope.
• Test consumers: vainfo, mpv --hwdec=vaapi, Firefox via media.ffmpeg.vaapi.enabled, chromium-fourier 149 (regression check).
• Phase 1 success criterion (matching libva-multiplanar): boolean correctness — "libva accepted + providing access to hardware decoder for each codec." Performance metrics deferred.
• Phase 0 task 1: recover fresnel from the SDDM greeter crash-loop (per ~/.claude/plans/dynamic-forging-piglet.md). Recovery is bookkept as substrate work inside this campaign, not as a separate prereq.

Out of scope:

• Front-end libva (API library). Backend only.
• Other hardware (ohm + ampere/boltzmann are libva-multiplanar's iterations).
• AV1 (no decoder block on RK3399 supports it).
• Performance metrics — fresnel CPU/GPU benchmarking is a separate iteration after correctness lands.
• cros-codecs Rust replacement (per user_stance_rust.md).
• Bootlin / Collabora upstreaming default-deferred (per feedback_no_upstream.md). Same discipline as libva-multiplanar.
• KWin / panfrost / Mali-T860 work — orthogonal until proven otherwise; a parallel kwin-fourier-fresnel campaign would be a separate decision.

Process

8(+1) phase loop per feedback_dev_process.md. Phase 0 substrate is in phase0_findings.md. Phase 5 review uses the sonnet-architect subagent pattern (Plan with model: sonnet).

In-session-acquired data discipline per feedback_replicate_baseline_first.md: libva-multiplanar's ohm-side measurements are reference history, not threshold sources for fresnel-fourier cells.

Predecessor work this campaign builds on

• ../libva-multiplanar/ — five closed iterations on ohm. Read in order:
  • README.md — current state, codec scope, file map.
  • phase8_iteration5_close.md — most recent close. The iter5-end backend is the substrate fresnel-fourier starts from.
  • phase0_findings.md (and phase0_findings_iter[2-5].md) — locked-scope precedent for codec breadth and consumer matrix on ohm; useful frame-of-reference when locking fresnel-side scope.
  • phase8_iteration1_close.md — iter1 surface-export DMA-BUF lifecycle race + multi-resolution cache + 64-pitch alignment bugs. Likely re-surface candidates on RK3399.
• ../libva-multiplanar/libva-v4l2-request-fourier/ — the fork itself. 12 commits ahead of bootlin tip plus iter1..iter5 work. git log for the actual landing record.
• ~/.claude/plans/dynamic-forging-piglet.md — fresnel SDDM greeter crash diagnosis + recovery plan. Phase 0 task 1 picks up from here.
• ~/src/fourier_attribution/ — ohm-only attribution matrix. The chromium-fourier WHEAT-but-fragile verdict and Cell E (vanilla Chromium 149 control) item are ohm-side context, not fresnel data.

External reference (carry-over from libva-multiplanar):

• Mozilla bug 1833354 / 1965646 (Firefox HW decode on RK35xx via libva-v4l2-request).
• Bootlin upstream bootlin/libva-v4l2-request — dormant since 2021.
• Linux kernel drivers/staging/media/rkvdec/ — RK3399 rkvdec H.264/HEVC/VP9 control protocol reference.
• Linux kernel drivers/media/platform/verisilicon/hantro_* — RK3399-vpu-dec MPEG-2/H.264/VP8 control protocol reference.

Repository layout

~/src/fresnel-fourier/                     <- this campaign (its own git repo)
├── README.md                              <- this file
├── phase0_findings.md                     <- locked research question + Phase 0 work list
├── (worklist.md, phase[2-8]*.md as phases land)
└── (the libva fork is NOT here — see ../libva-multiplanar/libva-v4l2-request-fourier/)

The campaign repo and the fork repo stay separate. fresnel-fourier commits its findings here; code changes to the backend land on the fork's master (or a branch named per the iteration if scope diverges from libva-multiplanar's ohm-side master).

Operator-facing repo URL: git.reauktion.de/marfrit/fresnel-fourier — created empty during scaffolding, no push until first iteration finds something worth publishing.

Non-upstreaming default

Inherited from libva-multiplanar / feedback_no_upstream.md. Patches must be aligned to upstream in syntax and semantics; PR/MR/bug-report only on explicit operator instruction.

Build infrastructure

distcc/cross-build path is the existing fleet: aarch64crosscompiler LXD on data, tesla LXD on hertz, dcc1 on dcw3. See reference_distcc_kernel_builds.md for invocation. Per the locked Phase 0 answer for libva-multiplanar (item 9), no distcc for libva builds — libva is small and links fast, hand-build on fresnel directly. Same default applies here unless a specific reason emerges.

For chromium-fourier 149 / firefox-fourier rebuilds against fresnel-side findings, the boltzmann LXD container path from libva-multiplanar iter3 is reusable.