On Fr, 2019-04-05 at 17:09 +0200, Linus K. wrote: > Hi, > I recently submitted this bug to https://bugzilla.kernel.org/ and was > redirected here. Hi, does your kernel have commit df3aa13c7bbb307e172c37f193f9a7aa058d4739 Author: Oliver Neukum <oneukum@xxxxxxxx> Date: Wed Sep 5 17:56:46 2018 +0200 Revert "cdc-acm: implement put_char() and flush_chars()" and commit 93e1c8a638308980309e009cc40b5a57ef87caf1 Author: Romain Izard <romain.izard.pro@xxxxxxxxx> Date: Fri Mar 22 16:53:02 2019 +0100 usb: cdc-acm: fix race during wakeup blocking TX traffic Regards Oliver