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uzbek-plus/logs/b23/B23-RESULT.md

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B23 — faster battery charging: LBC fast-charge current 450 → 720 mA (2026-10-07) — PASS, persistent

Change

One device-tree property only: &pm8916_charger { qcom,fast-charge-safe-current = <720000>; } (linux/dts/msm8916-jz08-aurora-b23.dts, includes the B18 DTB). The pm8916_lbc supervisor (v4, B10B-5) programs IBAT_SAFE and IBAT_MAX from it: code = current / 90 mA − 1 → 0x04 (450 mA) → 0x07 (720 mA). The simple-battery node has no constant-charge-current property, so the safe current is also the charge current. Kernel (7.2.7-aurora-b18), initramfs (B12Q) and cmdline are unchanged; the DTB differs from B18 only in this property and the model string.

Why not more: the LBC is a linear charger — PMIC dissipation is (VBUS − VBAT) · I; it has no input current limit, so a weak source sags below VIN_MIN (4.308 V) instead of limiting. 720 mA was the first step (hardware max 1440 mA).

RAM test (ram2, b23/b23-boot.sh, observer b23/b23-mon.sh every 30 s; nothing flashed)

  • Probe: IBAT_MAX 07, supervisor INIT → CHARGING, CHG_STATUS 05 (CC), FAST_CHG_ON + USB path 02, VDD_MAX 08 (4.20 V).
  • Source = laptop USB port: USB meter 0.724 A; USBIN 4.67–4.78 V, no sag.
  • CC held for 55+ min without restart/latch/FAULT (VADC VBAT under charge 3.98 → 4.10 V).
  • PMIC temperature: max 55.7 °C in the first 5 min, then 43–47 °C (part of the drop is the known ~7 °C backlight-off artefact of the PMIC sensor). Alert threshold 60 °C never reached.
  • CV (CHG_STATUS 03) from VADC ≈ 4.10 V; current then tapers (0.4 A on the meter) — normal, current does not speed up CV.

Persistent

  • Cache candidate b23/cache/mkfs-cache-b23.sh (B18 recipe, DTB b23) 01bfe522; lk2nd extlinux emulator (b23/cache/emu/run-emu-b23.sh): B18 regression identical, B23 boots label b23 with DTB 89eade0f, fault variants revert.
  • Written by b23/B23-write.sh (HW EDL): B23_CACHE_WRITE_VERIFIED — readback == image, all other partitions unchanged, pre-write cache readback == B18 ac82811a kept. Rollback: b23/B23-rollback.sh → B18 ac82811a.
  • Cold boot from eMMC (full power-off, no RESET): model "JZ08AU Aurora (B23 charge 720 mA)", IBAT_MAX 07, CHARGING.

Effect / limits

CC phase (empty → ≈ 4.1 V) ≈ 1.6× faster; the CV tail is unchanged. Board load (CPU, backlight) comes out of the same input current (no power path). Worst case (long CC from ≈ 3.7 V with CPU load) not yet measured thermally; still no thermal derating in the supervisor.