[pvrusb2] pvrusb2 timeout?

[Mike Isely]

On Thu, 21 Aug 2008, Dan Bodoh wrote:

> On Thu, Aug 21, 2008 at 9:14 AM, Mike Isely <isely at isely.net> wrote:
> >
> > On Wed, 20 Aug 2008, Dan Bodoh wrote:
> >
> >> Any ideas?  This timeout has occurred occasionally, but now twice in
> >> the last couple of days.  I'm running Ubuntu 8.04 with stock drivers
> >> (2.6.24-19).
> >>
> >
> > it simply got stuck and never recovered.  Unfortunately I've never seen
> > the problem happen and nobody else has seen it either, so nothing ever
> > developed from this.  But what you are saying here sounds like the same
> > issue.
> 
> After sending this last night, I found that it actually happened
> several times over the past few days, ending up with some recordings
> at 0 length.  Every time in the past when I noticed this, I had
> rebooted everything immediately, and the problem went away.  This
> time, I hadn't rebooted, so the problem stuck around.  Strange thing
> is, some recordings failed completely, some worked perfectly fine, and
> some didn't record at all during this "flaky" time.  Last night, after
> this post, I rebooted everything.
> 
> Prior to this most recent event, it's been months since I've seen this problem.

Strange.


> 
> > Another thing to consider:  Has anything recently changed in your
> > hardware / software?  Did this problem just suddenly start happening, or
> 
> No changes in the last few days that would directly correlate.  Within
> the last month, I did updated Ubuntu, but that didn't include a kernel
> or myth update.  I'm running on the stable 8.04 (no 'proposed' repo).

Has the room in which the device sits gotten any warmer?  Have there 
been any power glitches that might be different than before (e.g. turn 
on the air conditioner)?


> 
> >> In the kernel logs - nothing at 20:00, but first message after 20:00
> >> is at 20:41:
> >>
> >> Aug 20 20:41:05 mythbox kernel: [888366.618809] pvrusb2: Encoder timed
> >> out waiting for us; arranging to retry
> >> Aug 20 20:41:05 mythbox kernel: [888366.618820] pvrusb2: Encoder command: 0x82
> >> Aug 20 20:41:05 mythbox kernel: [888366.619087] pvrusb2: Error
> >> recovery initiated
> >> Aug 20 20:41:05 mythbox kernel: [888366.619091] pvrusb2: Retrying
> >> device reconfiguration
> >
> > Unfortunately that message is "normal".  Every once in a while the
> > encoder chip will wedge itself when we try to stream with it.  This
> > behavior has been observed for YEARS, and I've never been able to find
> > out the trigger.  However the driver detects this and recovers by
> > reloading and reconfiguring the encoder.  The whole recovery happens in
> > a second or two.  This timeout only ever happens at all at the moment
> > streaming is started.  Once it is going, I've never seen the encoder
> > crash.  The upshot of all this is that while it's an interesting clue
> > that this happened at the point when you got the backend timeout, this
> > might not be the "smoking gun".
> 
> 
> You may have misunderstood.  This message coincided with the point in
> time when my failed recording successfully restarted (41 minutes in to
> the program).  So whatever code is behind this message "fixed" the
> problem.
> 

Wow.  I sure did misunderstand.  This sounds a lot like the mpeg encoder 
chip crashed WHILE streaming.  I've never seen that happen here.  What 
the code you refere to did to "fix" this was to completely reinitialize 
the mpeg encoder chip: The chip is reset, reloaded with its firmware, 
restarted, and then re-sent all the configuration information.

One clue, however feeble, here is that you said it ran for months 
without a problem and then a rash of problems happened.  The mpeg 
encoder should not ever be crashing mid-stream.  However it is the 
"hottest" chip in the device, and I have heard stories of others who 
have seen heat related issues.  I imagine if that chip really does 
overheat, then what you are seeing might be a possible set of symptoms.  
If the FX2 continues operating (this is the microcontroller which 
controls the device as a whole), then the device will still be "working" 
overall.  And the FX2 is not a big energy consumer.  So if it is getting 
too hot, the first part to be impacted would be the encoder chip.  This 
is why I asked if the ambient temperature in the room might have 
recently gone up.

A possible experiment might be to run the device for a while with a fan 
blowing across it (and possibly the cover off).  That might not be a 
"solution" but it would yield an important clue if this is a heat issue.

Another (even more feeble) possibility is that something is glitching 
the power.  The device's power supply is just a simple wall-wart and 
therefore lacks all the filtering and energy storage of a big PC power 
supply.  Simple glitches which a PC won't notice will impact the 
PVR-USB2 device.  This has been seen by others.  One person correlated 
device crashes with his home's air conditioner cycling on/off.  However 
I'm not too hopeful of this cause because unlike the heat theory above, 
such power glitches will probably crash the entire device, FX2 included.  
In that case you should see evidence of the entire device acting as if 
it had been unplugged then re-plugged back into the USB port.

  -Mike


-- 

Mike Isely
isely @ pobox (dot) com
PGP: 03 54 43 4D 75 E5 CC 92 71 16 01 E2 B5 F5 C1 E8