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From:   Jesse Hathaway <jesse@mbuki-mvuki.org>
Date:   Thu, 4 Apr 2019 10:41:29 -0500
Message-ID: <CANSNSoXOmExO2RSp1gS8myUuiDpva4=0GeGpv+t8+X9p0u0H_w@mail.gmail.com>
Subject: Re: Regression causes a hang on boot with a Comtrol PCI card
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     Bjorn Helgaas <helgaas@kernel.org>, Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        Mathias Nyman <mathias.nyman@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-usb@vger.kernel.org
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On Tue, Apr 2, 2019 at 9:29 AM Alan Stern <stern@rowland.harvard.edu> wrote:
> Most likely the problem occurs somewhere inside
> quirk_usb_handoff_xhci().  Can Jesse add debugging statements to that
> routine in order to pin down exactly where the problem lies?

Alan,

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);

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.