Current state of things: I've tracked down the code line where the freeze happens. It's in function ehci_halt within file ehci-hcd.c. The function is executed on shutdown as well as when the usb devices on the bus are about to be probed again. The latter is triggered by "lsusb -v" as root. Apparently, the hardware misbehaves by not responding to a "readl" call.
As a workaround, it is possible to compile kernel 4.2 with a patch that disables the unused EHCI USB bus. However, this is *not* a generic solution! The same chip may be built into other computers, and the EHCI bus may be used there. ** Patch added: "Patch to blacklist the problematic EHCI bus. This is a workaround, NOT a solution!" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1485057/+attachment/4462350/+files/blacklist-evil-ehci-device.diff -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1485057 Title: "lsusb -v" as root freezes the kernel on Acer ES1-111; also freeze on shutdown To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1485057/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
