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From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: Alan Stern <stern@rowland.harvard.edu>,
	Kishon Vijay Abraham I <kishon@ti.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, linux-usb@vger.kernel.org,
	chris.chiu@canonical.com, Mathias Nyman <mathias.nyman@intel.com>
Subject: Re: 5.14.14+ USB regression caused by "usb: core: hcd: Add support for deferring roothub registration" series
Date: Tue, 16 Nov 2021 00:05:04 +0200	[thread overview]
Message-ID: <5158300e-946e-a0e8-e341-c569ed398dec@linux.intel.com> (raw)
In-Reply-To: <3cfc755c-7559-306c-bec4-ae87052fc7c0@linux.intel.com>

On 4.11.2021 1.54, Mathias Nyman wrote:
> On 3.11.2021 16.59, Alan Stern wrote:
>> On Wed, Nov 03, 2021 at 08:14:35PM +0530, Kishon Vijay Abraham I wrote:
>>> + Alan, Chris, Mathias, linux-usb
>>>
>>> Hi Hans,
>>>
>>> On 03/11/21 6:18 pm, Hans de Goede wrote:
>>>> Hi,
>>>>
>>>> On 11/3/21 10:07, Greg Kroah-Hartman wrote:
>>>>> On Wed, Nov 03, 2021 at 10:02:52AM +0100, Hans de Goede wrote:
>>>>>> Hi Greg,
>>>>>>
>>>>>> We (Fedora) have been receiving multiple reports about USB devices stopping
>>>>>> working starting with 5.14.14 .
>>>>>>
>>>>>> An Arch Linux user has found that reverting the first 2 patches from this series:
>>>>>> https://lore.kernel.org/all/20210909064200.16216-1-kishon@ti.com/
>>>>>>
>>>>>> Fixes things (the 3th patch is just some mostly unrelated refactoring/cleanup).
>>>>>>
>>>>>> See here for the Arch-linux discussion surrounding this:
>>>>>> https://bbs.archlinux.org/viewtopic.php?pid=2000956#p2000956
>>>>>>
>>>>>> And here are 2 Fedora bug reports of Fedora users being unable to use their
>>>>>> machines due their mouse + kbd not working:
>>>>>>
>>>>>> https://bugzilla.redhat.com/show_bug.cgi?id=2019542
>>>>>> https://bugzilla.redhat.com/show_bug.cgi?id=2019576
>>>>>>
>>>>>> Can we get this patch-series reverted from the 5.14.y releases please ?
>>>>>
>>>>> Sure,
>>>>
>>>> Thanks.
>>>>
>>>>> but can you also submit patches to get into 5.15.y and 5.16-rc1
>>>>> that revert these changes as they should still be an issue there, right?
>>>>
>>>> Yes I assume this is still an issue there too, but I was hoping that
>>>> Kishon can take a look and maybe actually fix things, since just
>>>> reverting presumably regresses whatever these patches were addressing.
>>>>
>>>> We've aprox 1-3 weeks before distros like Arch and Linux will switch
>>>> to 5.15.y kernels.  So we have some time to come up with a fix
>>>> there, where as for 5.14.y this is hitting users now.
>>>
>>> Is the issue with PCIe USB devices or platform USB device? Is it specific to
>>> super speed devices or high speed device?
>>
>> Look at the bug reports.  They are on standard PCs (so PCIe controllers) 
>> and some of them involve full speed (mouse and keyboard) devices.  
>> Although it looks like the problem has little to do with the device and 
>> a lot to do with the controller.
>>
>> Is there a good way to get more information about what is going wrong?  
>> For example, by enabling tracepoints in the xhci-hcd driver?
>>
>> Alan Stern
>>
> 
> To enable xhci traces and dynamic debug at boot please add:
> "usbcore.dyndbg=+p xhci_hcd.dyndbg=+p trace_event=xhci-hcd trace_buf_size=80M"
> to the kernel cmdline before booting.
> (info added to https://bugzilla.redhat.com/show_bug.cgi?id=2019788 as well)
> 
> Symptoms look similar to an old race issue where two usb devices were reset at the same time.
> xHC HW can't handle this, and to prevent it the hcd->address0_mutex was added.
> 
> for details see: 
> https://lkml.org/lkml/2016/2/8/312
> 
> -Mathias
> 

Looks like it really is an issue with address0_mutex in hub.c not preventing
two xhci slots from entering default state at the same time during retry.

Seems extending the mutex across retries resolved this, details:
https://bugzilla.redhat.com/show_bug.cgi?id=2019788

I'll post that patch here on linux-usb for review shortly

-Mathias

  reply	other threads:[~2021-11-15 22:05 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-03  9:02 Hans de Goede
2021-11-03  9:07 ` Greg Kroah-Hartman
2021-11-03 12:48   ` Hans de Goede
2021-11-03 14:44     ` Kishon Vijay Abraham I
2021-11-03 14:59       ` Alan Stern
2021-11-03 23:54         ` Mathias Nyman
2021-11-15 22:05           ` Mathias Nyman [this message]
2021-11-03 17:45     ` Greg Kroah-Hartman
2021-11-05  7:57   ` Greg Kroah-Hartman

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