Empirical Phase 7 verification revealed the algorithm bug: data links
in MEDIA_IOC_G_TOPOLOGY connect PAD IDs, not entity IDs directly.
My iter7 Phase 6 commit compared link source_id/sink_id against
the proc entity_id, never matched → io_entity_ids stayed empty →
interface lookup never fired → returns -1 → falls back to legacy
hardcoded path.
Topology dump on fresnel /dev/media0 (rkvdec) confirmed:
- Entity 3 (rkvdec-proc) has function=0x4008 (DECODER) ✓
- Data link src=16777218 sink=16777220 — these are PAD ids
(0x01000002, 0x01000004), NOT entity 3.
- Interface link src=50331660 (interface) sink=1 (entity) — for
interface links source/sink ARE entity IDs.
Fix: resolve pads → entities via the topo.pads[] array.
1. Collect pads belonging to proc entity (via pads[].entity_id).
2. For each data link touching those pads, the OTHER pad's
entity_id is an IO neighbor.
3. Find interface link to those IO entities (unchanged from prev).
Also allocate topo.pads[] in the 2-call ioctl pattern.
Signed-off-by: claude-noether <claude-noether@reauktion.de>
Anchors campaign-wide claims with measured numbers. Runs four
consumer configurations against $FIXTURE for $DURATION seconds each:
1. mpv --hwdec=vaapi (DMA-BUF zero-copy through libva)
2. mpv --hwdec=vaapi-copy (HW decode + VAImage readback)
3. firefox (iter5-amend, sandbox enabled, file:// URL)
4. mpv --hwdec=no (SW decode baseline / control)
Captures per consumer: CPU% (median + p90 from pidstat), GPU freq
median (from /sys/class/devfreq/fde60000.gpu/cur_freq, polled at
100ms cadence), drops in window (from mpv --term-status-msg),
p50 frame interval (mpv only), VmRSS delta (from /proc/PID/status).
Emits a markdown table with raw numbers per consumer — no aggregation,
no improvement ratios, no curated-benchmark framing. Honest schema
including '—' for measurements not available per consumer (e.g.
Firefox drops without internal hooks).
Phase 5 sonnet review caught 3 issues, all addressed before commit:
1. pidstat $8 column heuristic — replaced with header-driven %CPU
field detection (robust across sysstat 12.x point releases)
2. GPU freq median computation used /dev/stdin in nested subshell-
over-pipe (unreliable) — replaced with temp-file path
3. --frames=$((DURATION * 30)) hardcoded 30fps (fixture-hardcoding
per feedback_no_fixture_hardcoding.md) — replaced with
--length=$DURATION (wall-time bounded, framerate-agnostic)
Plus minor: empty cpu_pct.log now emits ERR rather than silent 0,
distinguishing measurement failure from "process used no CPU."
Reproducibility surface: run date, host, kernel, driver sha256,
fixture path+size, duration captured in the output markdown.
Hardware constants (/dev/video1, /dev/media0, devfreq path,
driver install path) are documented as PineTab2 (RK3566 via
hantro/rk3568-vpu) specific.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
claude-noether
claude-noether