From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Daniel Ritz <daniel.ritz@gmx.ch>
Subject: Re: [PATCH] uvcvideo: add another YUYV format GUID
Date: Thu, 10 Dec 2009 02:46:27 +0100
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Cc: Mauro Carvalho Chehab <mchehab@infradead.org>, linux-media@vger.kernel.org,
       linux-kernel@vger.kernel.org
References: <1259711324.13720.20.camel@MacRitz2> <200912032115.30431.laurent.pinchart@ideasonboard.com> <1259892337.2335.34.camel@MacRitz2>
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Hi Daniel,

On Friday 04 December 2009 03:05:37 Daniel Ritz wrote:
> Hi Laurent
> 
> On Thu, 2009-12-03 at 21:15 +0100, Laurent Pinchart wrote:
> > Hi Daniel,
> >
> > On Wednesday 02 December 2009 00:48:44 Daniel Ritz wrote:
> > > For some unknown reason, on a MacBookPro5,3 the iSight
> >
> > Could you please send me the output of lsusb -v both with the correct and
> > wrong GUID ?
> 
> sure. i attached three files:
>   isight-good.txt, isight-bad.txt, isight-good2.txt
> 
> this is three reboots in a row from like 10 minutes ago. the first
> boot into linux was actually rebooting from OSX...first cold boot
> today directly into linux had the right GUID.

Thanks. diff'ing the descriptors shows something interesting (from good to 
good2):

@@ -264,7 +264,7 @@
         dwMaxVideoFrameBufferSize      614400
         dwDefaultFrameInterval         333333
         bFrameIntervalType                 11
-        dwFrameInterval( 0)         3758429717
+        dwFrameInterval( 0)            333333
         dwFrameInterval( 1)            363636
         dwFrameInterval( 2)            400000
         dwFrameInterval( 3)            444444

3758429717 is 0xe0051615 in hex, and 333333 is 0x00051615.

I wonder what other parts of the descriptors could get corrupted that way.

> > > _sometimes_ report a different video format GUID.
> >
> > Sometimes only ? Now that's weird. Is that completely random ?
> 
> yes, sometimes only. it seems to be related to reboots, but i don't
> know what exactly triggers it. rmmod/modprobe doesn't trigger it.
> also, when the wrong GUID is reported, the only way of fixing it is
> to reboot. it really is just the GUID. even when the wrong one is
> reported, the device works just fine.
> 
> i started with a plain ubuntu 9.10, kernel 2.6.31 which was supposed
> to fail, so i upgraded to a 2.6.32-rc8 to fix the iSight and some other
> things, just to see it fail again. a reboot later and it worked, some
> time and reboot later it failed again...

All of those are warm reboots, and you don't boot any alternative OS in-
between, right ?

Does Linux reload the iSight firmware at every boot ? If it does, could you 
try to reload the firmware manually when you get a "bad" GUID to see if it 
helps ? You will probably need to unload the uvcvideo driver before reloading 
the firmware.

-- 
Regards,

Laurent Pinchart
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