On Thu, 4 Apr 2019, Jesse Hathaway wrote: > On Thu, Apr 4, 2019 at 12:16 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > > I added debug statements to quirk_usb_early_handoff, quirk_usb_disable_ehci & > > > ehci_bios_handoff. The box hangs right before calling: > > > > > > pci_write_config_byte(pdev, offset + 3, 1); > > > > Right _before_ that line? Not _after_ it? > > Sorry I should have been more precise, it hangs executing the above > pci_write_config_function. I get the debug printk immediately preceding > that line. > > > That's surprising because the two preceding lines of code are the > > condition of an "if" statement and a dev_dbg() call. I don't see how > > either of them could cause a hang. > > > > Maybe the hang is a delayed reaction to something happening somewhere > > else. But on the assumption that it isn't, you could try commenting > > out various parts of ehci_bios_handoff to see which ones make a > > difference. > > will do > > > > which is in ehci_bios_handoff: > > > > > > [ 10.698240] DEBUG: Passed quirk_usb_early_handoff 1300 > > > [ 10.704271] DEBUG: Passed quirk_usb_early_handoff 1308 > > > [ 10.710206] DEBUG: Passed quirk_usb_disable_ehci 939 > > > [ 10.715949] DEBUG: Passed quirk_usb_disable_ehci 945 > > > [ 10.721685] DEBUG: Passed quirk_usb_disable_ehci 950 > > > [ 10.727423] DEBUG: Passed quirk_usb_disable_ehci 958 > > > [ 10.733160] DEBUG: Passed quirk_usb_disable_ehci 964 > > > [ 10.738897] DEBUG: Passed quirk_usb_disable_ehci 968 > > > [ 10.744633] DEBUG: Passed ehci_bios_handoff 849 > > > [ 10.749884] DEBUG: Passed ehci_bios_handoff 884 > > > > > > I have attached the debug output, and my modified pci-quirks.c file > > > to the bug report, let me know what else I can do to help. > > sorry I attached them to the bug report, but I have attached them to this > email as well. Okay. You could try skipping that pci_write_config_byte() call. The following loop would probably time out, and you might find that the code crashes later on. You could also try setting try_handoff to 0 near the start of the routine. Your system plus the Comtrol PCI card could have the same sort of bug as reported in Bugzilla #77021. Alan Stern
