enricobuehler 3aacec53d8 fix(encode): RGB-direct must not engage on unaligned modes — the EFC reads past the capture buffer (GPU hang) ...

Field report (commit 25624443, RDNA2/VCN3 host, 1080p): repeated VCN0 VM
protection faults from punktfunk-host, vcn_enc_0.0 ring timeouts, two ring
resets, then a failed reset escalating to a full MODE1 GPU reset with VRAM
loss. Root cause is B1's RGB-direct source: the session's coded extent is
64x16-aligned (1920x1088) but the captured dmabuf is only the real mode
size (1920x1080) — the VCN EFC reads the 8 padding rows past the end of
the buffer (8 x 7680 B = 61 KB, matching the faulting page span exactly).
The CSC shader absorbs alignment by clamping reads and duplicating edges;
RGB-direct has no such stage. Every prior validation surface happened to
be aligned (256x256 smoke, 1440p live box) — 1080p is the common mode
that is not. The stall watchdog's rebuild-and-refault loop then turned a
per-session fault into the GPU death spiral.

Two layers:
- Open-time gate: RGB-direct engages only when the real mode equals the
  aligned coded extent (720p/1440p/4K yes, 1080p no); otherwise the CSC
  path runs and the verdict line says why (unaligned-mode). The padded-
  copy variant that re-enables 1080p is design-doc B2 work.
- Submit-time check: an RGB-direct frame that does not cover the coded
  extent errors out (encoder-rebuild path) instead of importing an
  undersized source.

On-glass (780M, host Mesa 26.0.4): all four smokes pass aligned; at
PF_SMOKE_W/H=250 the gate refuses RGB-direct and the rgb smokes soft-skip.
clippy clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

2026-07-20 20:23:29 +02:00

..

src

fix(encode): RGB-direct must not engage on unaligned modes — the EFC reads past the capture buffer (GPU hang)

2026-07-20 20:23:29 +02:00

Cargo.toml

perf(pyrowave): elevated GPU scheduling + global-priority encode queue

2026-07-19 01:02:01 +02:00