The Ch443 board A+B diagnostic captured a WARM-UP miss, not a displayed-
frame miss: the line-buffer reader is enabled by video_src_emif
immediately, but the HDMI mux only switches to it at the next vsync, and
the diagnostic (cleared only on !enable) froze that pre-display capture.
scan_y=32/nf=32 was the expected pre-display warm-up, and line_valid is
sticky so it only meant SOME row had loaded, not that row 32 was valid.
Two fixes (all accepted Ch443 timing repairs kept: AW buffer, F_SETTLE +
drain multicycle, tile max-skew, monolithic tex_mem):
1. Per-frame diagnostic: clear diag_valid_q on fs_edge_v as well as
!enable (mirrors underflow_v). Discards the warm-up capture and
records the first miss, if any, AFTER the real frame boundary.
2. Frame-restart latency: in L_R, after the single-beat response is
accepted, if fs_pending || fs_edge_e, abandon the remainder of the
obsolete row -- no beat commit, no next old-row AR, no publish/
increment -- and return to L_IDLE, which restarts at V_SOURCE_START.
Protocol-safe (the accepted AXI transaction is complete); removes up
to a full row of restart latency during vertical blanking, so the
restarted prefetch leads the first displayed row.
New tb_gs_scanout_restart proves: mid-fetch frame-start accepts the
in-flight response, issues NO further old-row AR, restarts at row 32,
loads rows 32/33 before active consumption, and no post-restart
underflow. Regressions green: scanout_lb {,_binomial,_hstretch,
_psm32_256,_fb}, scanout_diag (per-frame), ps2_hps_bridge, and the
complete f52 replay BYTE-IDENTICAL (Z 0/307200, COLOR 0/245760).
Also commits the previously-untracked Ch443 board A+B evidence
(docs/hardware/ch443_board_validation/: verdict, 3-session raw, board
FB, RBF sha). No Quartus/board/push from here.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Codex review containment/observability fixes (no behavior change, no redesign):
- scanout_lb: add !fs_edge_v to the diagnostic predicate so capture
matches the underflow latch's frame-start CLEAR priority exactly
(no capture on an fs_edge cycle the real latch suppresses).
- bridge: expose a destination snap_valid_q as 0x120[0] — set ON the
payload-capture edge, cleared on synced source-valid deassert — so
valid never leads the bundle by a cycle (was the middle sync stage).
- bridge: forced-synchronizer (SYNCHRONIZER_IDENTIFICATION FORCED) +
dont_merge/preserve on the underflow/read-error/valid chains;
preserve on the bundle capture regs (both domains).
- SDC: stage-0 async cuts on the three sync[0] inputs + the 37-bit
stable bundle hold-false-path + 2ns max_skew + 2ns net_delay, with
fail-closed src==37 / dst!=0 count checks (tile_ram_cdc idiom).
- tb_gs_scanout_diag: +fs_edge-suppression monitor (with coverage that
the coincidence is exercised), +valid-ordering monitor, +snapshot
stability after later misses, +production DUT (V_SOURCE_START=32,
stretch, linear) proving cold-start scan_y=32, +cause/phase packing.
32/32 checks pass.
- doc: production cold start is source row 32 (not 0), base+lookahead
may both assert, and one snapshot narrows but does not prove
starvation vs next_fetch CDC-lag.
Sim set all PASS: focused TB, tb_ps2_hps_bridge, scanout_lb
{binomial,hstretch,psm32_256}, complete f52 replay (FB byte-identical
Z 0/307200, COLOR 0/245760). No Quartus, board, push, or scanout
behavior change.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Preserve the Ch441 timing/renderer board-validation evidence and the
Codex-directed follow-up:
- FB reconciliation: the Ch437 A/B dump's 8-word first-beat delta was a
non-reproducible one-time transient; 3x render+dump and 8x pure-probe
re-reads all return golden d0047677 (words 0-7 correct). Memory integrity
confirmed deterministic. (fb_reconciliation.md)
- Structural audit + A-D diagnostic proposal for LPDDR_STATUS[5]: bit5 ORs
sticky CDC-synced underflow with AXI read-errors; dump path (arid=1) is
separate from scanout/HDMI (arid=3). Instrumentation proposal only, not
implemented. (scanout_status_bit5_proposal.md)
- Raw board logs, status samples, RBF hashes, A/B FB dump, board PNG.
No RTL edits, no compile, no builds.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
RTL (GS rasterizer, EE core stub, platform bridge, LPDDR4B path), sim regression
(272 TBs), docs, and tooling. Copyrighted PS2 content (BIOS, game code, GS dumps,
and all dump-derived textures/traces) is excluded via .gitignore and stays local.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
thejayman77