ricardgb opened a new pull request, #19450:
URL: https://github.com/apache/nuttx/pull/19450
# PR 1 — rp2040/rp23xx: preserve SIE_CTRL.PULLUP_EN in usbdev_register
Branch: `rp2040-rp23xx-pullup-en` (worktree `~/nuttxspace/wt-pr-pullup`)
Base: apache/nuttx master (1b6f918c3f)
Closes: #19434
## Summary
`usbdev_register()` in both `rp2040_usbdev.c` and `rp23xx_usbdev.c` clobbers
`SIE_CTRL.PULLUP_EN` immediately after the class driver asserted it, so a
cold-plugged device may never enumerate at all. One-line fix per chip: use
`setbits_reg32` instead of a wholesale `putreg32` when enabling EP0_INT_1BUF.
## Root cause
`CLASS_BIND` (composite_bind/cdcacm_bind) ends with `DEV_CONNECT`, which sets
`SIE_CTRL.PULLUP_EN`. Microseconds later `usbdev_register()` executes
`putreg32(EP0_INT_1BUF, SIE_CTRL)`, wiping the pull-up. Enumeration then only
succeeds if the host latched the microsecond pull-up blip and issued a bus
reset — the BUS_RESET handler re-arms the pull-up via
`CLASS_DISCONNECT -> DEV_CONNECT`. A warm host port catches the blip; a
cold-plugged port is still in attach debounce, misses it, and `PULLUP_EN`
stays 0 forever: total USB silence while NuttX runs normally underneath.
This presents as an intermittent, image/timing-dependent "cold boot brick".
Full investigation record (register dumps of the bricked state, breadcrumb
trace of the strip + host-blip rescue, A/B image data) is in #19434.
## Validation
- **RP2350 (Raspberry Pi Pico 2 W), hardware:** an image that failed 0/10
dmesg-verified cold plugs enumerated 10/10 after the fix; a second board
that had never enumerated anything was recovered by the fix on first boot.
Bricked-state diagnosis confirmed on live silicon: `SIE_CTRL = 0x20000000`
(EP0_INT_1BUF only, PULLUP_EN=0) with all classes registered and software
believing it was connected.
- **RP2040:** identical code, identical fix; build-tested
(raspberrypi-pico:usbnsh) — no RP2040 hardware validation performed, but
the RP2350 validation exercised the same logic.
## Impact
Any RP2040/RP23XX USB device application that is cold-plugged (or powered on
while attached to an already-powered host port that is slow to notice the
blip). No behavior change other than the pull-up surviving registration.
## AI disclosure
This investigation and fix were performed by an AI agent (Claude Code),
operated and directed by the submitter, and reviewed by the submitter before
posting.
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