uzbek-plus/logs/b10/b10b2/B10B2-RESULT.md

B10B2-RESULT — upstream pm8916_lbc charger, RAM only

Date: 2026-10-03. Verdict: PASS with a caveat (see "Not verified"). aboot/cache untouched, eMMC writes = 0, no manual PMIC writes before or after probe. Boot class A (RTC 5 s) via RESET-held lk1st fastboot.

Image / DT

• kernel 7.2.7-aurora-b10b2 = b10b1 + CONFIG_CHARGER_PM8916_LBC (linux/aurora-b10b2.config).
• DTB linux/dts/msm8916-jz08-aurora-b10b2.dts = B10B-1 + &pm8916_usbin { disabled }, &pm8916_charger { okay; monitored-battery; qcom,fast-charge-safe-voltage = 4200000; qcom,fast-charge-safe-current = 500000 }, &pm8916_bms { power-supplies = <&pm8916_charger> }, &usb/&usb_hs_phy { extcon = <&pm8916_charger> } → USB extcon has exactly one owner (charger@1000, USB=1; verified in the DTB and live).
• simple-battery unchanged from B10B-1 (3000 mAh, 3.4 V, 4.20 V B10 cap; the cell allows 4.35 V — not used).
• image b10/b10b2/out/aurora-b10b2.img 9f8a9096 (build-b10b2.sh), driver b10b2-boot.sh K, observer b10b2-mon.sh N P (reads only, ALERT on VBAT > 4.22 V / PMIC > 60 °C). out/ contains the B8F initramfs (PSK) → never publish.

Baseline before probe (baseline-b10b1.txt, baseline-summary.txt; running B10B-1, same lk1st path)

CHG_STATUS 05, CHGR RT 20, CHG_CTRL 90, VDD_MAX/SAFE 08/08 (4.20 V), IBAT_MAX/SAFE 00/0a (90/990 mA), VIN_MIN 04 (4308 mV), TCHG_MAX_EN/TCHG_MAX 80/1d (timer on, 120 min), IBATTERM 0x105B 09, COMP_OVR1 (VBAT_DET override) 00, BOOT_DONE 80, 0x1643 0b, USB 0x1308/0x1309 02/90, USB RT 03, BAT_IF 0x1208 83, BAT RT 03, USB IRQ cfg 0x1311/15/16 02.

Charger driver writes (diff-probe.txt, full PMIC diff vs baseline)

reg	before → after	meaning
0x1044 IBAT_MAX	00 → 04	450 mA (500 mA requested; 90 mA hardware step: 500000/90000 − 1 = 4)
0x1045 IBAT_SAFE	0a → 04	450 mA
0x1049 CHG_CTRL	90 → a0	CHG_EN + PSTG_EN (bit4 cleared, bit5 set)
0x1060 TCHG_MAX_EN	80 → 00	upstream disables the charger safety timer (0x1061 stays 1d)
0x1040 VDD_MAX / 0x1041 VDD_SAFE	08 → 08 (written, same value)	4.20 V
Untouched: VIN_MIN, IBATTERM/termination (0x105B 09), COMP_OVR1/VBAT_DET (00), BOOT_DONE (80), WDOG, BAT_IF, USB IRQ config (same as with pm8916_usbin).
All other diffs are dynamic data (ADC 0x31/32/33xx, BMS 0x40xx data, RTC). Exactly as predicted from the driver source.

sysfs pm8916-lbc-chgr (type USB): online 1, constant_charge_current 450000, constant_charge_voltage_max 4200000. BMS status → Charging.

Observation (ram1-mon.txt, ram1-mon-table.txt; 22 samples × 30 s, uptime 54–686 s, then stopped on purpose)

• State: CC/fast charge the whole time (CHG_STATUS 05, CHGR RT 20 = FAST_CHG_ON), USB path 02/90, USB RT 03, BAT RT 03, online 1.
• VADC VBAT: 3.80 → 3.8235 V; after the noisy LTE/Wi-Fi start-up a steady rise 3.8086 (295 s) → 3.8235 (686 s) ≈ +2.3 mV/min. BMS FIFO 13316 → 13433 (diagnostic; BMS voltage_now still ×300 µV, ≈5.5 % high, not used for decisions).
• USB meter (operator): 0.357 A during kernel boot, then 0.355 A, peaks 0.38 A.
• PMIC die temp 44 → 48–49 °C (plateau), CPU 45–47 °C. No ALERT. VBAT far below 4.22 V.
• CV and termination were not reached (estimated 2.5–4 h more from VBAT 3.82 V).

BOOT_DONE / the earlier ~0.08 A

boot	BOOT_DONE	IBAT_MAX	USB meter	VBAT trend
cache (lk2nd extlinux), class A	00	00 (90 mA)	0.15–0.41 A	charging, terminated after ~45 min (B10A)
RAM via lk1st fastboot, no LBC driver (B10B-0/1)	80	00 (90 mA)	≈0.08 A	flat / draining under load (ram1 drained to ≈3.7 V in ~7.7 h)
RAM via lk1st fastboot + pm8916_lbc (B10B-2)	80 (before and after probe)	04 (450 mA)	≈0.36 A	rising ≈2.3 mV/min
With BOOT_DONE = 1 the input/charge current follows IBAT_MAX: the ~0.08 A in B10B-0/1 was IBAT_MAX = 90 mA under BOOT_DONE, not another
cause. Without BOOT_DONE (cache boots) the LBC evidently ignores the 90 mA field (autonomous current). BOOT_DONE = 0 with IBAT_MAX = 450 mA
could not be tested in a RAM boot (lk1st always sets BOOT_DONE in fastboot). The USB meter shows the whole board, not the battery current;
the conclusion rests on meter + VADC VBAT trend together.

Other subsystems

LTE START OK 74.1 s, ping via wwan0 10/10 (snapshot 3/4 during start-up); Wi-Fi AP enabled 78.8 s, Pronto running; NCM/telnet and gadget (UDC configured) fine with the LBC extcon; display errors 0 (fbcon/panel up); eMMC w=0.

Not verified (caveat)

Hardware termination and the (expected) absence of automatic recharge with upstream pm8916_lbc were not observed in this run (low initial SOC, multi-hour duration, and the driver disables the safety timer, so an unattended multi-hour RAM charge was not accepted). Absence of software recharge is established by the code audit (B10A-DRIVER-AUDIT: only the usb_vbus IRQ is handled). The full cycle termination → VBAT drop → restart is to be tested in B10B-3 with a recharge supervisor.

After the test

Monitor stopped (host and board side). The LBC registers written by the driver (IBAT_MAX 450 mA, timer off, CHG_CTRL a0) and BOOT_DONE live in the PMIC retained domain and survive a warm/class-B reboot → return to SBL defaults needs a full power-off (battery out ≥ 90 s) = class A.

Bench reset after B10B-2 (class-A power cycle, no RESET; post-classA-check.txt)

Operator: USB out → battery out → ≈2.5 min → battery in → USB in. Boot 14:39 = normal cache B9C (7.2.7-aurora-b9c), RTC 3 s → class A. Read-only snapshot: CHG_STATUS 05, VDD_MAX/SAFE 08/08, IBAT_MAX 00, IBAT_SAFE 0a, VIN_MIN 04, CHG_CTRL 90, IBATTERM 09, TCHG_MAX_EN/TCHG_MAX 80/1d, COMP_OVR1 00, USB 0x1308 02, BOOT_DONE 0x1642 00, 0x1643 00, PON_REASON1 10, POFF2 00. → All LBC registers back at SBL1 defaults; the bench is clean.