On Mon, Jul 20, 2020 at 08:16:05PM +0200, Michal Hocko wrote: > On Mon 20-07-20 13:48:12, Alan Stern wrote: > > On Mon, Jul 20, 2020 at 07:45:30PM +0200, Michal Hocko wrote: > > > On Mon 20-07-20 13:38:07, Alan Stern wrote: > > > > On Mon, Jul 20, 2020 at 06:33:55PM +0200, Michal Hocko wrote: > > > > > On Mon 20-07-20 11:12:55, Alan Stern wrote: > > > > > [...] > > > > > > sudo echo 'module usbcore =p' >/debug/dynamic_debug/control > > > > > > > > > > > > Then wait long enough for some interesting messages to appear in the > > > > > > kernel log (it should only take a few seconds if the worker thread is as > > > > > > busy as you say) and collect the output from the dmesg command. > > > > > > > > > > > > To turn dynamic debugging back off when you're finished, use the same > > > > > > command with "=p" changed to "-p". > > > > > > > > > > [ 95.395815] hub 2-0:1.0: state 7 ports 6 chg 0006 evt 0000 > > > > > [ 95.395824] usb usb2-port1: status 0088, change 0000, 5.0 Gb/s > > > > > [ 95.395838] usb usb2-port2: status 0088, change 0000, 5.0 Gb/s > > > > > [ 95.396016] hub 2-0:1.0: hub_suspend > > > > > [ 95.396023] usb usb2: bus auto-suspend, wakeup 1 > > > > > [ 95.396029] usb usb2: bus suspend fail, err -16 > > > > > > > > Okay, that's the problem. You may get more specific information about > > > > the suspend failure if you turn on dynamic debugging for the xhci-hcd > > > > module (same command as above but with xhci-hcd instead of usbcore). > > > > > > Would that help to pinpoint the problem down? > > > > It might. I can't say for sure without seeing the output. > > echo 'module xhci-hcd =p' >/sys/kernel/debug/dynamic_debug/control > > doesn't yield to any output. I have tried both with and without usbcore > debug output enabled. In the former there is no new output and for the > later I get the same I have posted earlier. Sorry, my mistake. The module name needs to be "xhci_hcd" with an '_' character, not a '-' character -- the same as what shows up in the lsmod output. You could also try collect a usbmon trace from the .../2u file. It does seem that bus 2 is where the problem occurs. Alan Stern
