[+cc Andreas, linux-kernel] On Wed, Aug 24, 2016 at 05:40:53PM +0100, Richard van der Hoff wrote: > I'm having problems with a Plugable USB-C docking station, with my > laptop, a Dell XPS 13 (9350). If the docking station is plugged in > at boot, it works correctly; however, when I hotplug it after boot, > the USB devices are not detected until I force a rescan of the PCI > bus. > > I have also raised this as a bug at > https://bugzilla.kernel.org/show_bug.cgi?id=151261. There are some > dmesg traces and lspci logs attached to that bug. > > The lspci output suggests a chain of three PCI bridges (00:1c.0, > 01:00.0, 02:02.0) before a PCI->USB bridge (05:00.0 or 39:00.0). If > I boot without the docking station plugged in, 01:00.0 and beyond do > not appear, and nor do they appear on hotplug. However, if I hotplug > the docking station and then force a rescan with "echo 1 > > /sys/bus/pci/devices/0000:00:1c.0/rescan", the PCI bridges and USB > devices appear and spring into life. > > My impression, and feedback from the linux-usb mailing list, is > therefore that this is a PCI hotplug problem. Please include a pointer to the linux-usb analysis. > There are some ACPI errors in the dmesg at hotplug but they don't > really mean much to me. >From https://bugzilla.kernel.org/attachment.cgi?id=227331 (dock present at boot): 00:1c.0 PCI bridge: Intel Device 9d10 (PCIe Root Port) Bus: primary=00, secondary=01, subordinate=39 01:00.0 PCI bridge: Intel Device 1576 (Alpine Ridge Thunderbolt) Bus: primary=01, secondary=02, subordinate=05 02:02.0 PCI bridge: Intel Device 1576 (Alpine Ridge Thunderbolt) Bus: primary=02, secondary=05, subordinate=05 05:00.0 USB controller: Intel Device 15b5 (Alpine Ridge USB 3.1) 01:00.0 and 02:02.0 are ports of a Thunderbolt switch. Since they don't appear when you boot without the docking station, the dock connection must be between 00:1c.0 and 01:00.0. >From the kernel's point of view, plugging in the dock would be a PCIe hotplug event on 00:1c.0 that should be handled by pciehp. Do you have pciehp included in your kernel? Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
