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jetson-customize-clocks

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Use to lock/cap Jetson CPU/GPU/EMC clocks, toggle EMC/CPU DVFS, or change cpufreq governors by editing BPMP DTB and nvpower.sh pre-flash. Do NOT use for live tuning or nvpmodel edits.

When to use

• The **BPMP DTB** at `Linux_for_Tegra/bootloader/<BPFDTB_FILE>` — per-clock `max-rate-custom` ceilings, plus the EMC DVFS gate (bwmgr + cactmon on all SoCs; osp-controller on T26x only).
• **nvpower.sh** at `Linux_for_Tegra/rootfs/etc/systemd/nvpower.sh` — cpufreq / devfreq governors and (optionally) per-device min / max / static rates written to sysfs at boot.

When not to use

• **Image-build-time only.** All edits land under `<source.root_path>/Linux_for_Tegra/` and reach the device only via `/jetson-promote-image` → `/jetson-flash-image`. Live-target tuning is out of scope.
• **`max-rate-custom` only lowers the ceiling.** It must be strictly below `max-rate-maxn`; raising the silicon cap is not supported.
• **Effective ceiling is two-layer.** The runtime ceiling is `min(BPMP cap, active-nvpmodel-mode cap)`. The nvpmodel cap is owned by `/jetson-customize-nvpmodel`; this skill does not edit it.
• **SoC-conditional EMC DVFS gate.** Disabling EMC DVFS requires editing different node sets on T23x (bwmgr + cactmon) vs T26x (bwmgr + cactmon + delete `osp-controller`). Mis-detection produces undefined behavior.
• **T23x GPU cap is multi-node.** The GPU clock is split across `nafll_gpusys` and every `nafll_gpcX`; the cap binds only when applied to all of them.
• **`nvpower.sh` is package-managed.** It ships in `nvidia-l4t-init`; package upgrades clobber in-place edits. Long-lived setups should prefer a systemd drop-in or sibling helper.
• **ODMDATA wins.** When an ODMDATA token covers a property, the token overrides direct BPMP DTS edits at flash time. Direct BPMP DTS edits are the fallback for properties no NVIDIA token reaches.
• **`max-rate-maxn` and `lateinit` are off-limits.** `max-rate-maxn` is the silicon ceiling (read-only). `lateinit` is for boot-time clock init, not ceiling overrides — never touch either.

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