On Mon, Jan 2, 2017 at 2:28 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Mon, 2 Jan 2017, Chris Murphy wrote: > >> crossposting linux-usb@ and linux-pci@ >> >> I filed a bug https://bugzilla.kernel.org/show_bug.cgi?id=191681 but >> was told I need to post to the list first. I'm not actually sure this >> is a USB bug, as filed in the bug report, because I think this >> USB-C/Thunderbolt port is really a PCIe port that needs to become a >> USB port only once the adapter is connected. >> >> Anyway, the gist of the problem is that if the USB-C to USB 3 adapter >> is connected at boot time, the kernel doesn't instantiate a USB port >> at all. So if for example I have a USB flash drive connected to the >> adapter with a Linux live OS on it, the firmware sees the stick, finds >> the bootloader, the bootloader finds and loads the kernel and >> initramfs - so clearly up to this point it's working properly. But >> then I end up at a dracut shell because there's not root fs to be >> found. And there's no rootfs because there's no USB bus at all as far >> as the kernel is concerned. >> >> If the adapter is not connected at boot time, is connected later on, >> it all works as I'd expect it to work. I can plug it in, unplug it, >> plug it back in, and it always works fine. So weirdly it's just a "if >> connected at boot time" something is becoming deeply confused. >> >> I've tested 4.10-rc1 from kernel.org; but it's been a problem since >> kernel 4.7.7 at least. The bug report has lspci, dmidecode, and two >> dmesg outputs from boots with the adapter connected at boot time, and >> not at boot time (but connected later). That bug report is 4.10-rc1 >> based with CONFIG_PCIEASPM_DEBUG=y >> CONFIG_PCI_DEBUG=y but I'm not really seeing much additional >> information that helps figure out what the source of the problem is. > > Considering that the failed boot log contains no USB messages at all, > and no messages referring to PCI bus 0000:37 (the bus associated with > the adapter), this certainly looks like a PCI problem. I see these lines in the problem case, which don't occur in the working case. [ 0.561046] pci_bus 0000:37: busn_res: [bus 37-ff] end is updated to 37 [ 0.561047] pci_bus 0000:37: busn_res: can not insert [bus 37] under domain [bus 00-ff] (conflicts with (null) [bus 00-fe]) [ 0.579446] pci 0000:37:00.0: can't claim BAR 0 [mem 0xb0000000-0xb000ffff]: address conflict with PCI Bus 0000:00 [mem 0x40000000-0xdfffffff window] [ 0.602277] pci 0000:37:00.0: can't derive routing for PCI INT A [ 0.602280] pci 0000:37:00.0: PCI INT A: not connected [ 0.612304] pci 0000:37:00.0: xHCI HW not ready after 5 sec (HC bug?) status = 0xffffffff -- Chris Murphy -- 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
