ricardgb opened a new pull request, #19371:
URL: https://github.com/apache/nuttx/pull/19371
## Summary
USB device controller drivers invoke `CLASS_DISCONNECT()` on every USB bus
reset, and a bus reset is the first step of normal host enumeration. Every
other class driver (`cdcacm`, `usbmsc`, `rndis`) re-asserts `DEV_CONNECT()` at
the end of its `disconnect()` handler ("perform the soft connect function so
that we can be re-enumerated"), so on controllers that soft-disconnect around
bus reset the pull-up glitch is microseconds long and invisible to the host.
`cdcecm_disconnect()` and `cdcncm_disconnect()` did not, so the first bus reset
of enumeration leaves a standalone CDC-ECM or CDC-NCM device soft-disconnected
and it never appears on the host. On RP2040, `rp2040_usbintr_busreset()`
explicitly drops the pull-up, so a standalone device never enumerates at all.
This mirrors the cdcacm behavior and performs the soft connect in both
`disconnect()` methods, unless part of a composite device (`composite.c`
already re-connects in its own disconnect handler).
Addresses the standalone CDC-ECM case of #15880 (root-cause analysis in
[this
comment](https://github.com/apache/nuttx/issues/15880#issuecomment-4915349759)).
## Impact
Standalone (non-composite) CDC-ECM and CDC-NCM devices become able to
enumerate on controllers that call `CLASS_DISCONNECT()` on bus reset. Composite
configurations are unaffected (the added call is guarded by
`!CONFIG_CDCECM_COMPOSITE` / `!CONFIG_CDCNCM_COMPOSITE`). Other class drivers
are unaffected; this makes cdcecm/cdcncm consistent with the existing
cdcacm/usbmsc/rndis convention.
## Testing
Validated on raspberrypi-pico (RP2040, arm-none-eabi-gcc 13.2, no new
warnings):
- **CDC-ECM (standalone `CONFIG_NET_CDCECM`)**: before this change the
device never appears on a Linux host (no enumeration at all); with this change
it enumerates via `cdc_ether` and ICMP ping across the link runs at 0% loss
(~0.5 ms RTT).
- **CDC-NCM (standalone `CONFIG_NET_CDCNCM`)**: before this change the
device never attaches; with this change it enumerates and binds the host
`cdc_ncm` driver. (Full NCM datapath on RP2040 is blocked by a separate,
pre-existing interrupt-IN endpoint delivery issue that also affects other
classes on this controller; under separate investigation.)
## Disclosure
This root-cause analysis, patch, and hardware validation were performed by
an AI agent (Claude Code, operated and directed by the submitter), and the
result was reviewed by the submitter before posting.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
https://claude.ai/code/session_01AHJRvWeBMTHwzpwjaUg4HW
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