POWER-FINAL-22 — dark DSI hand-over (no colour flash between logo and splash)

Status: SEALED, AWAITING THE OWNER FLASH (2026-10-13). Package out/y2linux-platform-v1-power-final-candidate-22/ (fallback = 21), receipts out/deep-sleep-final/build22-receipts/. BOOTIMG f73ba54c706d1d15612d8bfea7d1273b93a45293190da5a476f9f76fa8fb402b, Y2ROOT d7d21d71a397acb7d7e95d0f240c798e35da6d7068030844dc867854542e6a0d. Identity: build Y2LINUX-PLATFORM-V1-POWER-FINAL-22, kernel 6.18.56-y2linux-platform-v1-power-final-22, root 2026.08-platform-v1.52, release 1.0.0-platform-v1-power-final-candidate.22; Linux 430ff11 on main, Reborn unchanged (217e28d). Flash BOOTIMG + ANDROID only with MT6582_preserve_data_scatter.txt, Download Only. Sleep code identical to 20/21.

21 result (owner, 2026-10-13)

The white/colour screen after the shutdown animation is gone. The colour flash between the bootloader logo and the splash remained.

Cause (21 boot a0c4d60e, archive 118)

mtk-dsi: handoff: clocks on; park video at 0.489 s stops LK's video stream; Linux's first DSI modeset (from the fbdev client) streams at 0.532 s; the splash's first frame appears at 0.642 s. The lit panel had no stream for ≈40 ms. 21's splash-side darkening ran after the modeset and could not cover it.

What 22 changes

Overlay 0017-mt6582-dsi.patch (mtk_dsi.c, in display.ko loaded from the initramfs at ≈0.47 s): before "park video" the hand-over switches the panel's backlight (the DT backlight phandle of the panel node) off, only if it was lit; 50 ms after the first Linux atomic_enable it relights; a 3-s fallback relights if no enable comes, and a devm release relights on unbind or probe failure. Expected: logo → short dark → black → splash. 21's changes stay.

Tests

test_display_quiet_power (+ the hand-over order), test_overlay_hashes; locked-container production suite 693 cases, exit 0; package validation, ELF, installed ARM, privacy, inventory PASS.

What to check after the flash

Power on several times: no colour flash between logo and splash; dmesg | grep handoff shows backlight off until the first Linux frame then backlight restored. Shutdown stays dark. Then the sleep tests.