Re: Endless loop with "detected XactErr"

From: Zdenek Kabelac
Date: Fri Apr 08 2011 - 10:36:24 EST

2011/4/8 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>:
> On Thu, 7 Apr 2011, Zdenek Kabelac wrote:
>> Hi
>> I've been trying to track some resume error with Intel GPU - and
>> notice a couple problems related to resume of my Lenovo T61.
>> Laptop has been docked - and suspend/resume has been performed without
>> 'undocking' laptop.
>> After several iterations of suspend/resume - I've got this endless
>> printing loop with this line on console display:
>> ehci_hcd 0000:00:1a.7: detected XactErr len 0/4 retry 1
>> Just with changing last number - I've got only one such line on serial console.
>> By looking into  "drivers/usb/host/ehci-q.c"  - there seems to be
>> endless goto loop.
> It isn't endless.  You didn't notice the test against QH_XACTERR_MAX.

Maybe I've not been patient enough - but I'd been waiting for quite some time
and the console was just scrolling this line on display - so I need to
turn-off the machine.
(After like a minute of this looping)

>> From the log it looks like my USB mouse connected to docking station
>> was the source of problem.
>> (Maybe a movement ??)
> This particular error message indicates a hardware problem in the USB
> signals.  A bad contact, a bad cable, a device failure -- something
> like that.

Well it's been connected to Lenovo docking station - so unsure what
bad cable you mean here.
(and AFAICT it seems to work quite well all the time).

>> Here is the trace from last resume:
>> [  473.873802] ACPI: \_SB_.GDCK - undocking
>> [  473.897678] hub 2-0:1.0: state 7 ports 4 chg 0000 evt 0010
>> [  473.904809] ehci_hcd 0000:00:1a.7: detected XactErr len 0/4 retry 1
> And presumably additional lines containing similar messages.
> There's no real reason for them ever to stop, since they are only
> debugging messages.  If you turn off CONFIG_USB_DEBUG you'll never see
> tham.

You mean it's normal I get machine stuck in endless loop when I turn
on debugging ?
I though debug is there to debug the problem - not to add a new one ??
As this happened during suspend - I had no other option than to simply
turn off the machine.

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