phase 0 corrections: hantro RK3399 has no H.264; substrate is iter8 master

Two empirical corrections to the morning-of-2026-05-07 phase 0 lock,
based on V4L2 inventory + iter8 fork build smoke captured this evening
on fresnel (kernel 6.19.9-99-eos-arm).

Correction 1 — hantro-vpu-dec on RK3399 does not advertise H.264.

phase0_findings.md morning lock claimed both rkvdec (/dev/video3)
and hantro-vpu-dec (/dev/video5) advertise H.264. Empirical
v4l2-ctl --list-formats-out shows hantro-vpu-dec exposes only
MG2S (MPEG-2) and VP8F (VP8) — no S264. Likely carryover from
RK3568 (ohm) hantro, which does support H.264; the RK3399 hantro
kernel variant in drivers/media/platform/verisilicon/ registers
a different codec list. Fix:

  - README.md hardware-target table: drop "+ H.264" from Decoder
    block 2.
  - README.md decode-side surface-area paragraph: note hantro is
    MPEG-2 + VP8 only and that there is exactly one bind for H.264
    (rkvdec).
  - phase0_findings.md mechanism table: drop H.264 from /dev/video5
    row; correct DT compatible to rockchip,rk3399-vpu (the actual
    parent device compatible — sysfs reports rockchip,rk3399-vpu,
    not rockchip,rk3399-vpu-dec which is just the v4l2 card type
    string).
  - phase0_findings.md "H.264 lands on both blocks" sentence:
    inverted to "H.264 lands only on rkvdec".
  - phase0_findings.md Open Question #2 (two-block H.264 routing):
    marked RESOLVED 2026-05-07 evening (null). Single bind, no
    routing decision, one test cell per codec.

Empirical evidence: phase0_evidence/2026-05-07/v4l2_inventory_findings.md
(distilled from v4l2_inventory.txt — the latter is gitignored as
raw data, regenerable via the v4l2-ctl invocation documented in
the findings file).

Correction 2 — substrate is iter8 master (65969da), not iter5-end.

phase0_findings.md morning lock framed the substrate as "iter5-end
fork." That was true on 2026-05-05 (iter5 close); between then and
the 2026-05-07 fresnel-fourier scaffold libva-multiplanar continued
through iter6 (per-OUTPUT-slot REINIT request_fd binding), iter7
(slot-leak fix, cap_pool harness, msync verify harness, OUTPUT-pool
teardown), and iter8 (perf binding cell harness, RK3566/3568 doc
fix). Building from master tip 65969da inherits all the iter6-iter8
hardening at zero cost. Fix:

  - phase0_findings.md substrate paragraph: strikethrough the
    "iter5-end" framing, add corrected paragraph naming master
    tip 65969da and listing what iter6/7/8 added.
  - phase0_findings.md top-of-doc: add an "Empirical corrections
    2026-05-07 evening" callout linking to the evidence files,
    so a reader spotting the locked-vs-corrected mismatch knows
    where the empirical update came from.

Empirical evidence: phase0_evidence/2026-05-07/iter8_build_smoke.md
(clean build, vainfo profile enumeration, HEVC anomaly write-up).

What's preserved on purpose:

The strikethrough rendering in phase0_findings.md keeps the original
locked text visible alongside the correction — campaign convention
treats locks as historical record, not editable state. A reader
landing on the file from a deep link sees both the morning's
intent and the evening's empirical update. Git history has the
clean diff if anyone wants the original without strikethrough.

What's not changed:

The codec scope in the locked research question stays correct in
count — five codecs (H.264 + HEVC + VP9 + MPEG-2 + VP8). The
routing table changes (H.264 → rkvdec only; MPEG-2 → hantro only;
no shared block) but the boolean-correctness pass/fail criterion
per codec is unaffected. Phase 1 lock can proceed on the corrected
map without re-opening scope.

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

README.md

@@ -23,12 +23,12 @@ That campaign's README explicitly names fresnel (RK3399) and ampere/boltzmann (R
 | 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 + H.264 + VP8 |
+| 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`](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 **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.
+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.