jetson-customize-usb

Customize USB (per-port enable / disable / role)

Purpose

Enable, disable, or change the role of USB2 / USB3 SS ports on a
Jetson Thor (Tegra264) or Orin (Tegra234) custom carrier. Captures
per-port wiring (role, max speed, VBUS-EN / OC GPIOs, CC1/CC2 GPIOs
for Type-C, USB3 SS UPHY lane), resolves the SS to USB2 companion
graph from the in-tree DTB, then renders a self-contained kernel-DT
overlay that flips every port action in three places in lockstep
(lane status, port status, host xHCI phys + phy-names).

UPHY lane allocation belongs to jetson-customize-uphy. No ODMDATA
edit. Output is one commit to the composite custom overlay .dts in
the bsp_sources/ hardware repo.

Prerequisites

• Active profile with reference_devkit: + custom_carrier: blocks.
• <source.root_path>/Linux_for_Tegra/.git exists
  (/jetson-init-source).
• /jetson-derive-carrier has run — carrier flash-conf fork in the
  overlay tracker.
• /jetson-customize-uphy has run when any enabled USB3 SS port
  needs a non-stock UPHY lane allocation. Its JSON sidecar at
  <workspace>/target-platform/<profile-stem>.jetson-customize-uphy.json
  is consulted for SS lane allocation.
• Source-of-truth docs: Adaptation Guide §"Port the Universal Serial
  Bus", Module Design Guide §USB, SoC TRM (xusb block).
• When custom_carrier: is present, both
  documents.custom_carrier_schematic AND
  documents.custom_carrier_pinmux_xls are REQUIRED. Refuse the run
  if either is missing — per-port routing (VBUS-EN / OC / CC GPIOs, SS
  lane wiring, hub fan-out) on a custom carrier cannot be guessed.
  Reference-devkit-only profiles skip this check.
• dtc, fdtoverlay on PATH.

Overview

USB on Tegra spans three IP surfaces: the xusb_padctl block (USB2
OTG + USB3 SS PHYs), the tegra-xusb xHCI host controller, and an
optional tegra-xudc device controller attached to the single
OTG-capable USB2 port (usb2-0).

A per-port flip MUST touch three kernel-DT places in lockstep.
Anything less crashes the host xHCI probe and leaves lsusb empty
on every port (collateral damage to stock-okay ports):

#	Place	Path	What it controls
1	Lane (PHY provider)	xusb_padctl/pads/usb<2|3>/lanes/usb<2|3>-N	SS / OTG PHY hardware-binding. status="disabled" then lane stops providing a PHY.
2	Port (controller-binding)	xusb_padctl/ports/usb<2|3>-N	Per-port mode (host/device/otg), companion link, VBUS / OC / CC pin refs. status="disabled" then port removed from user-facing topology.
3	Host xHCI phys-list	bus@0/usb@<addr>.phys + .phy-names	Array of phandles + names the xHCI driver iterates. A ref to a disabled PHY returns -ENODEV and aborts the whole host probe.

NVIDIA's stock-disabled usb3-3 in the Thor base DTB is the canonical
pattern — all three places flipped in lockstep.

Two extra rules ride on top of the three-place pattern:

• Rule A — lane + port pairing. Lane (place 1) and matching port
  (place 2) MUST flip together.
• Rule B — companion cascade.
  xusb_padctl/ports/usb3-N.nvidia,usb2-companion references a USB2
  port phandle. Disabling that USB2 without cascading to its SS
  companion then tegra-xusb: failed to enable PHYs: -19.

Agentic, not table-driven — every port, controller, lane,
companion link, phandle, and __symbols__ lookup is resolved at
runtime from docs + DTB + carrier pinmap + schematic.

When to invoke

• The user says "enable USB", "disable USB hub", "configure USB3 SS",
  "set USB role", "wire VBUS-EN", "tegra-xusb / xudc / dr_mode", or
  asks to bring up / take down a USB controller on a custom carrier.
• A USB receptacle on the carrier doesn't enumerate after flash, OR
  collateral USB damage (lsusb empty after a previous
  jetson-customize-usb attempt) needs to be fixed.
• jetson-customize-uphy re-allocated UPHY lanes affecting USB3 SS
  ports and per-port DT now needs to follow.

Procedure (summary)

The full step-by-step procedure lives in references/procedure.md.

1. Step 1 — resolve active target + open source-of-truth docs.
2. Step 2 — build the USB topology + companion graph from the
   in-tree DTB.
3. Step 3 — AskUserQuestion for port(s) to enable / disable;
   surface companion cascade + on-carrier hub fan-out explicitly.
4. Step 4 — per-port verify (module + carrier + UPHY lane) and
   capture wiring (VBUS-EN / OC / CC GPIOs via pin_verifier.py).
5. Step 5 — render the kernel-DT overlay using the three-place
   pattern, append fragments (usb:padctl, usb:xhci, optional
   usb:xudc) to the composite custom overlay .dts, run
   fdtoverlay + the three post-merge invariants, commit to
   bsp_sources/.
6. Step 6 — write run-state JSON sidecar (shape in
   references/run-state-sidecar.md), emit headline, then drive the
   downstream next-step chain via sequential AskUserQuestion prompts
   per references/procedure.md Step 6. Never substitute a printed
   "Next step: …" line for the prompts.

See references/gotchas.md for the load-bearing failure modes.

Limitations

• Owns kernel-DT overlay only. ODMDATA does not expose a per-port
  USB status knob; do not edit it.
• Does NOT allocate UPHY lanes — jetson-customize-uphy owns that.
  Refuse to commit an SS-enable until uphy run-state shows the lane
  allocated.
• Does NOT directly patch the pinmux DTSI — routes SFIO mismatches
  to /jetson-customize-pinmux set-pin.
• Does NOT compile the .dtbo or register OVERLAY_DTB_FILE+= —
  /jetson-build-source owns build + flash-conf registration.
• Tegra platform invariant: only usb2-0 is OTG-capable; xudc
  attaches there only. All other USB2 ports and all USB3 SS ports
  are host-only.

Troubleshooting

• Empty lsusb on every port, USB-eth at 192.168.55.1 still up:
  host xHCI bailed; three-place lockstep was broken. Inspect merged
  DTB; verify post-merge invariants in references/procedure.md
  Step 5d.
• tegra-xusb: failed to enable PHYs: -19: companion cascade
  (Rule B) violated — a USB2 was disabled without its SS companion.
• no port found or Requested PHY is disabled: Rule A
  violated — lane status and port status are mismatched.
• FDT_ERR_NOTFOUND from fdtoverlay: a fragment used
  target = <&label> for a node whose label is not in
  __symbols__ (typical for host xHCI / tegra-xudc). Switch to
  target-path = "/bus@0/usb@<addr>".
• dtc warning phys_property: cell 0 is not a phandle reference:
  benign; expected when using raw integer phandles in the host phys
  override.
• Port boots but VBUS never asserts: vbus-supply references a
  regulator parent node that does not exist. Ensure the fixed
  regulator node is present before referencing it.
• xHCI binds the wrong port at boot: host phys element order
  was not preserved. Only elide disabled entries; never reorder
  kept ones.

References

• references/procedure.md — full step-by-step procedure.
• references/gotchas.md — load-bearing failure modes.
• references/run-state-sidecar.md — run-state JSON shape.
• references/usb-architecture.md — Tegra USB IP architecture
  notes (xusb_padctl, tegra-xusb, xudc).
• references/usb-dt-bindings.md — USB DT binding cheatsheet
  (lane / port / phys-list shapes).
• ../../scripts/pin_verifier.py — shared HSIO pin verifier.
• ../../references/platform_template.yaml — documents: block
  consumed by Step 1.
• ../../context/bsp-customization-workflow.md — overlay edit
  protocol.
• ../../references/bsp-customization-kernel-dtb.md — composite
  overlay append protocol.
• ../jetson-customize-uphy/SKILL.md — sibling skill that owns
  UPHY lane allocation.
• ../jetson-customize-pinmux/SKILL.md — sibling skill for
  VBUS-EN / OC / CC SFIO fixes.
• ../jetson-derive-carrier/SKILL.md — must run first.
• ../jetson-init-source/SKILL.md — produces the overlay tracker
  • bsp_sources repo.