On Sun, 22 Nov 2015, Daniel J Blueman wrote: > On 16 November 2015 at 23:22, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > On Mon, 16 Nov 2015, Daniel J Blueman wrote: > > > >> Tuning USB suspend [1] in 4.3 on a Dell XPS 15 9553 (Skylake), I see a > >> kworker thread spinning in rpm_suspend [2]. > >> > >> What is the most useful debug to get here beyond the immediate [3]? > > > > You can try doing: > > > > echo 'module usbcore =p' >/sys/kernel/debug/dynamic_debug/control > > kworker and ksoftirqd spinning occurs when I echo 'auto' to all the > USB control entries. Using Alan's excellent tip, we see this being > logged repeatedly at a high rate: > [ 353.245180] usb usb1-port4: status 0107 change 0000 > [ 353.245194] usb usb1-port12: status 0507 change 0000 > [ 353.245202] hub 1-0:1.0: state 7 ports 16 chg 0000 evt 0000 > [ 353.245203] hub 1-0:1.0: hub_suspend > [ 353.245205] usb usb1: bus auto-suspend, wakeup 1 > [ 353.245206] usb usb1: bus suspend fail, err -16 > [ 353.245207] hub 1-0:1.0: hub_resume > ... > > So, EBUSY. Both the webcam is not open, and the bluetooth interface > [1] is rfkill'd; the situation occurs even if I unload all related > modules. > > What further debug would be useful? > > Thanks! > Daniel > > -- [1] > > Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub > Bus 001 Device 002: ID 0a5c:6410 Broadcom Corp. > Bus 001 Device 003: ID 1bcf:2b95 Sunplus Innovation Technology Inc. > Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Since bus 1 uses an xHCI controller, you should do: echo 'module xhci-hcd =p' >/sys/kernel/debug/dynamic_debug/control I'm reasonably sure this will end up printing "suspend failed because a port is resuming", since that's the only place where xhci_bus_suspend() fails with -EBUSY, but you should try it to confirm this. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
