[Bug 219748] Pluggable UD-4VPD dock appears to continually reset with AMD AI 365

bugzilla-daemon
2025-03-04T08:44:17Z

--- Comment #16 from Mika Westerberg (mika.westerberg@linux.intel.com) ---
Thanks! So we have:

[ 56.773330] thunderbolt 0000:c6:00.6: 0:3: hotplug: scanning
[ 56.773335] thunderbolt 0000:c6:00.6: 0:3: hotplug: no switch found
[ 56.773349] thunderbolt 0000:c6:00.6: acking hot plug event on 0:2
[ 56.773362] thunderbolt 0000:c6:00.6: 0:2: hotplug: scanning
[ 56.773504] thunderbolt 0000:c6:00.6: 0:2: is connected, link is up (state:
2)
[ 56.773515] thunderbolt 0000:c6:00.6: 0:2: waiting for a while
[ 57.371077] thunderbolt 0000:c6:00.6: acking hot unplug event on 0:3
[ 57.371143] thunderbolt 0000:c6:00.6: acking hot unplug event on 0:2
[ 57.692761] thunderbolt 0000:c6:00.6: acking hot plug event on 0:3
[ 57.692828] thunderbolt 0000:c6:00.6: acking hot plug event on 0:2
[ 58.291125] thunderbolt 0000:c6:00.6: acking hot unplug event on 0:2
[ 58.291217] thunderbolt 0000:c6:00.6: acking hot unplug event on 0:3
[ 59.430462] thunderbolt 0000:c6:00.6: 0:2: .. done, trying to enumerate the
router

In other words there is some ~600ms timeout in the pluggable device that
triggers hot-remove and then hot-add if the device is not enumerated. This is
naturally the USB4 spec, as far as I can tell the host does not need to
enumerate the device at all actually.