linux-kernel - Re: uvcvideo causes ehci

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Date:	Wed, 21 Oct 2009 18:38:46 +0300
From:	Ozan Çağlayan <ozan@...dus.org.tr>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	linux-media@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	USB list <linux-usb@...r.kernel.org>,
	laurent.pinchart@...asonboard.com
Subject: Re: uvcvideo causes ehci_hcd to halt

Alan Stern wrote:

(Add uvcvideo maintainer to CC)
> [  420.737748] usb 1-5: link qh1024-0001/f6ffe280 start 1 [1/0 us]
>   
>
> The periodic schedule was enabled here.
>
>   
>> [  420.737891] usb 1-5: unlink qh1024-0001/f6ffe280 start 1 [1/0 us]
>>     
>
> And it was disabled here.  Do you have any idea why the uvcvideo driver 
> submits an interrupt URB and then cancels it 150 us later?  The same 
> thing shows up in the usbmon traces.
>
>   
>> [  420.741605] usb 1-5:1.0: uevent
>> [  420.741957] usb 1-5: uevent
>> [  420.745592] usb 1-5:1.0: uevent
>> [  420.807880] ehci_hcd 0000:00:1d.7: reused qh f6ffe280 schedule
>> [  420.807894] usb 1-5: link qh1024-0001/f6ffe280 start 1 [1/0 us]
>>     
>
> Now ehci-hcd tried to re-enable the periodic schedule.  Note that 
> this is 70 ms after it was supposed to be disabled.
>
>   
>> [  420.808780] ehci_hcd 0000:00:1d.7: force halt; handhake f7c6a024
>> 00004000 00000000 -> -110
>>     
>
> This error message means that the disable request from 70 ms earlier
> hasn't taken effect.  It looks like a nasty hardware bug -- the
> controller is supposed to disable the schedule no more than 2 ms after
> being told to do so.
>
> Has this device ever worked with any earlier kernels?
>   

I only tried 2.6.30.9 and 2.6.31.4, both of them is affected by the same
problem but sometimes it works without a problem so I think that this
can be interpreted as *at-least-working* on those kernels from time to time.

> A little more debugging information could confirm this.  After the
> error occurs, go into /sys/kernel/debug/usb/ehci/0000:00:1d.7 and post
> a copy of the "registers" file.  If there's anything of interest in the
> other files, post them too.
>   

OK I'll look at them tomorrow, Thanks.

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