[linux-dvb] Lost lock problems over extended periods of time

Andrew de Quincey adq_dvb at lidskialf.net
Wed Jun 8 23:34:49 CEST 2005


On Wednesday 08 June 2005 18:40, Oliver Endriss wrote:
> Andrew de Quincey wrote:
> > It seems I only need to set the tone when it loses lock. Here is my
> > current hack:
> > ...
> > When it dies, I see the following in dmesg:
> > DVB: LOST LOCK - attempting retune
> > DVB: REGAINED LOCK WITH SIMPLE TONE setting
> >
> > So what the hell would cause that? I've got printks in the
> > set_tone()/set_voltage()/etc functions, and nothing is calling them. All
> > it does once the initial lock is gained is request the frontend lock
> > status.
>
> Which frontend driver, iirc stv0299?

Yes. As far as I know all the cards I've seen with this problem are based on 
this frontend. 

Note though, most cards with this frontend are rock solid. In most cases, 
they're attached to the _same_ multiswitches as the ones with the problem.

> If some code would write to register 0x08, it might turn off the 22kHz
> tone. Check whether the corresponding register has been modified.

Already checked that - the register 0x08 remains the value I set last.

When the tone is set on for the first time during the tune:
CURRENT 0x08 value: 46
NEW 0x08 value: 47

However, when it loses the lock:
CURRENT 0x08 value: 47
NEW 0x08 value: 47

So I'm setting 0x08 to the _same_ value it is currently. Yet doing this causes 
the signal to be regained in less than 100ms. If I don't do this, lock is 
_never_ regained, no matter how long I leave it (however, if I retune by 
stopping+starting our application it locks immediately).

Incidentally, my latest test was to set the tone every 60 seconds in the 
frontend loop. This didn't work though - it still lost the lock, and went 
into the patch I posted earlier and regained it simply by setting the tone.




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