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>
rtl/gif_gs
GIF path and Graphics Synthesizer logic. Matches docs/contracts/gif_gs.md.
Current contents
-
gs_stub.sv— GS shell with two architecturally distinct write ports (Ch75 namespace split):reg_wr_*— privileged-block writes (16-bit offset within0x12000000). LatchesBGCOLOR(offset0x00E0) intobg_{r,g,b}; other offsets emitEV_MODE.gif_reg_*— GIF A+D register-number writes (8-bit reg# + 64-bit data). DecodesPRIM=0x00,RGBAQ=0x01,XYZF2=0x04,XYZ2=0x05,FRAME_1=0x4C,ZBUF_1=0x4Einto per-register 64-bit latches; unknown reg numbers emitEV_MODE.- No VRAM, no drawing yet — that is the next architectural step.
-
gif_path_stub.sv— Wave 2 minimal GIF packet logger; project-local single-qword register-write format. Used bytb_bgcolor_via_dma. -
gif_packed_stub.sv— real PS2 GIFtag parser (Ch72-Ch75). Handles PACKED (FLG=0), REGLIST (FLG=1), IMAGE (FLG=2), DISABLE (FLG=3). TheREAL_AD_REG_MAPparameter selects the A+D dispatch port:REAL_AD_REG_MAP=0(default, back-compat) — drivesgs_stub.reg_wr_*using a project-local 16-bit offset carried inin_data[79:64].REAL_AD_REG_MAP=1— drivesgs_stub.gif_reg_*using the real PS2 8-bit reg# carried inin_data[71:64]. Source-of-truth: PCSX2GSRegs.h.
BGCOLOR reset value
At reset, bg_{r,g,b} default to 0x40 each (mid-grey) rather than black.
Rationale: this makes "gs_stub reset but no BGCOLOR write yet" visually
distinct from "video output disabled / black frame" in Milestone A. Override
is a BGCOLOR write from the test harness.
Pitfall: namespace conflation
Ch74 conflated GIF A+D reg numbers with GS privileged-block offsets and
mapped e.g. 0x14→PMODE@0x0000. That is fiction — those are separate
namespaces. Ch75 split them. ZBUF_1 is 0x4E, not 0x4F (that's
ZBUF_2). When adding a new GIF-context register, source the reg# from
PCSX2 GSRegs.h, never from the privileged-block map.