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>
claude-noether
6df2159dd3