On Wed, Oct 28, 2020 at 03:54:35PM +0100, Helge Deller wrote: > On 10/27/20 10:00 AM, Johan Hovold wrote: > > On Thu, Oct 08, 2020 at 08:16:02PM +0200, Helge Deller wrote: > >> My testcase is pretty simple: > >> 1. I use e.g. "minicom -D /dev/ttyUSB2". Serial connection works. > >> 2. I exit minicom. > >> 3. I suspend the workstation: "systemctl suspend" > >> 4. I wake up the machine and wait a few seconds. > >> 5. I start "minicom -D /dev/ttyUSB2" again. No transfers on the serial port. > >> > >> With my patch the minicom serial communications does work. > >> Another way to wake up the connection is to rmmod the driver and > >> insmod it again. > > > > Weird indeed. If you exit minicom before suspend and no other process is > > keeping the port open, then that write_latency_timer() above would never > > be executed. > > > > Could you enable some debugging and provide a dmesg log from a test > > cycle (open/close minicom, suspend/resume, open minicom)? > > > > echo file usb-serial.c +p > /sys/kernel/debug/dynamic_debug/control > > I enabled the debugging and tried a few times, but somehow I can not > reproduce the issue any longer. > > So, please drop my patch for now. Good to hear the problem's gone. :) Let us know if you run into it again. Johan
