On Mon, 20 Jan 2020 13:52:15 -0700 Paul Zimmerman <pauldzim@xxxxxxxxx> wrote: > On Mon, 20 Jan 2020 10:23:11 -0500 (EST) Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > > On Sun, 19 Jan 2020, Paul Zimmerman wrote: > > > > > I reported this regression last week (see > > > https://lore.kernel.org/linux-usb/20200115153714.03d5b3aa@EliteBook/T/#u) > > > but I got no response to my email. Today I have retested with > > > 5.5-rc7 and verified that the problem still exists. So I am > > > resending with a different subject line to see if anyone responds. > > > > > > The $subject patch causes a regression on my HP EliteBook laptop > > > with a built-in USB bluetooth adapter. About 50% of the time, a > > > suspend/resume cycle will cause the bluetooth adapter to stop > > > working. > > > > > > The dmesg log below shows two suspend/resume cycles. At time > > > 63.928 you can see the bluetooth adapter being successfully > > > resumed, and at time 140.969 you can see it fail. After reverting > > > the patch, the bluetooth adapter resumes 100% of the time. > > > > > > I also included below a lsusb -v of the bluetooth adapter. Is > > > there any other debugging info you'd like me to send? > > > > It looks like your dmesg log was made without enabling debugging > > messages in usbcore. Can you collect another log with debugging > > messages turned on? > > > > echo 'module usbcore =p' > > >/sys/kernel/debug/dynamic_debug/control > > > > Also, it might not hurt to collect and post a usbmon trace for a bad > > suspend-resume cycle. > > Hi Alan, > > Thanks for responding. The new dmesg log and the usbmon trace are > below. The dmesg shows a good suspend/resume followed by a bad one. > The bluetooth device is usb 2-3.2 I believe. The usbmon trace is only > for the failed suspend/resume case. I did some more debugging on this using ftrace, here is an annotated log that shows what I think is happening on a failed resume. Note that hub_port_connect_change() is the function that the patch modified to call usb_get_device_descriptor() in some circumstances. This first call to hub_port_connect_change() is for a different device, not the failing one. There are multiple other calls to that function in the trace, but they are not for the device in question: kworker/1:6-19987 [001] 7803.175058: funcgraph_entry: | hub_port_connect_change() { kworker/1:6-19987 [001] 7803.175069: funcgraph_entry: ! 11911.151 us | usb_get_device_descriptor(); kworker/2:5-20675 [002] 7803.179333: funcgraph_entry: | usb_probe_interface() { Starting here is a worker thread that is trying to setup the bluetooth adapter after the resume: kworker/u17:1-3175 [002] 7803.179457: funcgraph_entry: | hci_power_on() { kworker/u17:1-3175 [002] 7803.179458: funcgraph_entry: | hci_dev_do_open() { kworker/u17:1-3175 [002] 7803.179468: funcgraph_entry: | btusb_setup_intel() { kworker/2:5-20675 [002] 7803.179480: funcgraph_exit: ! 147.596 us | } And here is a worker thread that is handling the connect change on the USB port with the bluetooth device. This happens while the btusb_setup_intel() function called by the other thread above is still running: kworker/3:1-16790 [003] 7803.181323: funcgraph_entry: | hub_port_connect_change() { kworker/3:1-16790 [003] 7803.181330: funcgraph_entry: | usb_get_device_descriptor() { kworker/0:2-19962 [000] 7803.184885: funcgraph_entry: 6.016 us | hub_port_connect_change(); kworker/0:2-19962 [000] 7803.187208: funcgraph_entry: 5.462 us | hub_port_connect_change(); kworker/1:6-19987 [001] 7803.187835: funcgraph_exit: ! 12776.810 us | } kworker/1:6-19987 [001] 7803.187846: funcgraph_entry: ! 767445.344 us | hub_port_connect_change(); By this point the failure has happened ("Bluetooth: hci0: Reading Intel version information failed (-110)") , and it looks like somebody queues another work to try setting up the bluetooth adapter again: hciconfig-21074 [000] 7803.193549: funcgraph_entry: | hci_dev_open() { kworker/1:6-19987 [001] 7803.955315: funcgraph_entry: ! 144039.307 us | hub_port_connect_change(); kworker/u17:1-3175 [003] 7805.203325: funcgraph_exit: ! 2023855 us | } kworker/u17:1-3175 [003] 7805.211728: funcgraph_exit: ! 2032269 us | } kworker/u17:1-3175 [003] 7805.211731: funcgraph_exit: ! 2032273 us | } hciconfig-21074 [000] 7805.211760: funcgraph_entry: | hci_dev_do_open() { hciconfig-21074 [000] 7805.211777: funcgraph_entry: ! 3069605 us | btusb_setup_intel(); And here the usb_get_device_descriptor() call made by the USB worker thread finally completes. It also fails ("kworker/3:1 timed out on ep0in len=0/18"): kworker/3:1-16790 [003] 7808.277224: funcgraph_exit: ! 5095893 us | } hciconfig-21074 [001] 7808.283313: funcgraph_exit: ! 3071554 us | } hciconfig-21074 [001] 7808.283315: funcgraph_exit: ! 5089767 us | } So if I'm understanding this correctly, there are two threads that are trying to access the USB bluetooth device at the same time. I have no idea if that is how it's supposed to work. Thanks, Paul
