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Subject: Re: Regression causes a hang on boot with a Comtrol PCI card
To:     Alan Stern <stern@rowland.harvard.edu>,
        Bjorn Helgaas <helgaas@kernel.org>
Cc:     Jesse Hathaway <jesse@mbuki-mvuki.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
References: <Pine.LNX.4.44L0.1904021028110.1562-100000@iolanthe.rowland.org>
From:   Mathias Nyman <mathias.nyman@linux.intel.com>
Message-ID: <d1070139-5b14-f42a-938f-2fe51779642b@linux.intel.com>
Date:   Tue, 2 Apr 2019 17:49:08 +0300
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On 2.4.2019 17.29, Alan Stern wrote:
> On Mon, 1 Apr 2019, Bjorn Helgaas wrote:
> 
>> [+cc Mathias, Greg, Alan, linux-usb]
>>
>> Beginning of thread: https://lore.kernel.org/linux-pci/CANSNSoWiKd98Dt1N2sSjP9Af8zk1NPV-=3P4VLtFs_cSQG4RUg@mail.gmail.com
>>
>> Synopsis: v5.0 hangs at boot unless the following commits are reverted:
>>
>>    1302fcf0d03e ("PCI: Configure *all* devices, not just hot-added ones")
>>    1c3c5eab1715 ("sched/core: Enable might_sleep() and smp_processor_id() checks early")
>>
>> The hang appears to be in quirk_usb_early_handoff().  With
>> "initcall_debug", we see the call but not the completion:
>>
>> On Fri, Mar 22, 2019 at 03:02:11PM -0500, Jesse Hathaway wrote:
>>>> So apparently the hang happens while we're running the "final" PCI
>>>> fixups.  This happens after all the rest of PCI is initialized.
>>>>
>>>> Can you boot v5.0 vanilla with "initcall_debug"?  Maybe we can narrow
>>>> it down to a specific quirk.
>>>
>>> yup, added the "initcall_debug" output to the ticket:
>>> https://bugzilla.kernel.org/show_bug.cgi?id=202927, here is the tail end
>>>
>>> [   14.896337] NET: Registered protocol family 1
>>> [   14.901314] initcall af_unix_init+0x0/0x4e returned 0 after 4866 usecs
>>> [   14.908694] calling  ipv6_offload_init+0x0/0x7f @ 1
>>> [   14.914238] initcall ipv6_offload_init+0x0/0x7f returned 0 after 1 usecs
>>> [   14.921821] calling  vlan_offload_init+0x0/0x20 @ 1
>>> [   14.927365] initcall vlan_offload_init+0x0/0x20 returned 0 after 0 usecs
>>> [   14.934948] calling  pci_apply_final_quirks+0x0/0x126 @ 1
>>> [   14.941106] pci 0000:00:1a.0: calling  quirk_usb_early_handoff+0x0/0x6a0 @ 1
>>>
>>> thanks, Jesse Hathaway
> 
> 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 Stern
> 

lspci log from bugzilla shows 0000:00:1a.0 is a EHCI device,
so probably woth adding debugging to quirk_usb_disable_ehci() as well

00:1a.0 USB controller: Intel Corporation C610/X99 series chipset USB Enhanced Host Controller #2 (rev 05) (prog-if 20 [EHCI])

-Mathias