From 264cc68ff29d64411a561d506d2918c8ba5cde35 Mon Sep 17 00:00:00 2001 From: mikkeli Date: Fri, 9 Oct 2026 00:25:46 +0900 Subject: [PATCH] USB report: unplug and replug of hub PD measured separately Unplug causes the full USB-C detach (~3.5 s total). Replug causes no detach but ~10 s of disruption: the tablet goes silent while the Orin's link stays up, then reconnects its gadget once. Only an app-level heartbeat would see the replug outage. Co-Authored-By: Claude Opus 5.5 --- docs/impl/reports/USB-TABLET-LINK.md | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/docs/impl/reports/USB-TABLET-LINK.md b/docs/impl/reports/USB-TABLET-LINK.md index 0e320b9..82d814c 100644 --- a/docs/impl/reports/USB-TABLET-LINK.md +++ b/docs/impl/reports/USB-TABLET-LINK.md @@ -89,11 +89,26 @@ Three PD unplug/replug cycles while pinging the tablet every 0.5 s: | 2 | 00:14:38.5 | 00:14:43.6 | 3.1 s + 1.5 s | | 3 | 00:14:51.4 | 00:15:02.0 | 11.8 s | -- **Each cycle caused exactly one full detach** (`fusb301_detach`), not one per transition. The hub resets its data port on one of - the two PD edges; which one can't be seen from the Orin side. +- **Each cycle caused exactly one full detach** (`fusb301_detach`), not one per transition. The separate-edge test below shows + it is the unplug. - Each detach follows the same pattern: re-attach after about 0.5 s, then the `l4tbr0` bridge ports flap about three times over 5–10 s (the tablet re-creating its USB network) before settling. - Recovery is automatic every time: the same DHCP lease, normal ping (~3 ms) afterwards. Nothing needs fixing on the Orin. +#### Each edge separately (same day, one 60 s window each) + +| | PD unplugged (00:23:04) | PD plugged back (~00:24:12) | +|---|---|---| +| USB-C detach on the Orin | **yes**, full detach and re-attach | **no** | +| Orin link (`l4tbr0` ports) | flapped twice, stable after 3.4 s | stayed up; one short gadget reconnect at 00:24:21.6 (0.7 s) | +| Ping lost | 3.1 s | 5.0 s while the Orin's link was **up**, then 0.3 s and 1.5 s | +| Total disruption | ~3.5 s | ~10 s | + +- Unplug: the hub cuts its data port, so the Orin sees a real disconnect, and recovery is quick. +- Replug: no disconnect on the Orin's side. The tablet stops answering for about 5 s (most likely renegotiating power and switching to + charging), then re-creates its USB network once. **The Orin's interface state does not reveal this outage**, so only an + application-level heartbeat catches it. +- Exact replug time isn't known; the first failed ping is used as its marker. + Consequence: in the car, expect a link outage of up to about 12 s at every ignition change. That is a requirement for the services (failure detection and redelivery; project-yukart ARCHITECTURE decision 24), not something to fix in the host setup.