Session 29 — 2026-03-28c — GCC CNOC Clock Research; ABL v2.3 Source Ready

Session 29 — 2026-03-28c

FieldValue
Date2026-03-28
Phase03b2 — Boot mode selection
Duration~2 h

GCC/CNOC Clock Architecture for SDM660/636

No dedicated GCC_TLMM_AHB_CLK exists. TLMM sits on the CNOC (Config NOC) bus. Three CBCR clocks needed:

ClockRegisterAddress
GCC_SNOC_CNOC_AHB_CBCRGCC+0x40180x00104018
GCC_CNOC_PERIPH_SOUTH_AHB_CBCRGCC+0x501C0x0010501C
GCC_CNOC_PERIPH_NORTH_AHB_CBCRGCC+0x50200x00105020

Source: boot_images/QcomPkg/Sdm660Pkg/Library/ClockTargetLib/ClockHWIO.h. CBCR enable protocol: write bit 0 = 1, poll bit 31 until 0. RMSK = 0x80000005. GCC base itself is safe to access from ABL (cannot be clock-gated by the clocks it manages).

ABL v2.3 Design

  • Boot path: reverted to v1.6 equivalent — all hall sensor MMIO removed. Boot path is clean.
  • oem test-sensor: live GCC CNOC clock enable + TLMM GPIO read. If fastboot hangs, power-cycle recovers (no bootloop risk).
  • NV attempt counter and watchdog removed — unreliable (NV doesn’t survive resets). Not needed for fastboot-only approach.

Source prepared, not yet built. Device needs PBL 9008 recovery first (still bootlooping on v2.2).

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