From f14202047fa234d809d08f0c95ed5b794ae1285c Mon Sep 17 00:00:00 2001 From: Mikkeli Date: Sun, 11 Oct 2026 15:49:06 +0900 Subject: [PATCH] ADB in the car: the PD hub causes the NCM packet loss; adb push stays slow without it Co-Authored-By: Claude Opus 5.5 Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz --- docs/ADB-IN-CAR.md | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/docs/ADB-IN-CAR.md b/docs/ADB-IN-CAR.md index cc5e68a..354ad81 100644 --- a/docs/ADB-IN-CAR.md +++ b/docs/ADB-IN-CAR.md @@ -106,7 +106,20 @@ Tested with the tablet on the Orin, charging through the PD hub: 165 MB debug APK install failed, and so will `flutter run`'s first install. The app's own traffic (small, 5 Hz) is unaffected so far. -Until the link loss is understood, install at the desk over USB, and use the car -path for `logcat`, `shell` and screenshots. Suspects, untested: the NCM gadget's -packet aggregation on the Orin's 5.15 kernel, the PD hub, USB power management on -either side. The gadget also offers RNDIS, which would be the first comparison. +**The PD hub causes the packet loss.** With the tablet on a plain C-to-C cable +straight to the Orin, ping loss is 0% at every size, even at 100 packets/s, and a +raw one-way TCP transfer Orin → tablet runs at **~4.3 MB/s** with 4 retransmits +in 20 MB. + +**adb push is still slow without the hub: ~0.14 MB/s, 175 retransmits in 20 MB**, +against 4 for the raw transfer. Cause not found. A bulk transfer running beside a +ping burst loses nothing, so it is not simply traffic in both directions. + +Until both are understood, install at the desk over USB, and use the car path for +`logcat`, `shell` and screenshots. The car still needs the PD hub to charge the +tablet, so the hub, or its replacement, needs its own test. + +A test trap: commands started from `adb shell` on the tablet use Android's +default network (WiFi), not the USB link. `nc 192.168.55.1 …` from there gets +no route. Only sockets bound to the Ethernet network, as the app's are, take the +link.