[linux-dvb] Re: Drivers not reporting TIMEDOUT

[Johannes Stezenbach <js@linuxtv.org>]

Nico Sabbi wrote:
> Andrew de Quincey wrote:
> >>>There's another problem: ghost locking. If you 1) tune to a "good"
> >>>frequency, then 2) tune to a wrong one,
> >>>often the FE_READ_STATUS on the wrong one (2) reports FE_HAS_LOCK,
> >>>even though the frontend
> >>>didn't lock at all, so it seems it's reporting the FE_HAS_LOCK related
> >>>to 1).
> >>>This happens both on my Nova-S and on my Airstar2 with yesterday's
> >>>dvb-kernel and all previous versions
> >>>that I used.
> >>>That's why I added && (locks < 2) in the while loop.
> >>>     
> >>>
> >>sounds like a bug in the dvb_frontend.c code...
> >
> >Strange, never seen this myself. FE_READ_STATUS goes direct to the 
> >hardware so it shouldn't be possible. What frontends are on those cards?
> 
> it's very easy to reproduce: in ~/.tzap/channels.conf change the 
> frequency of a good channel ('B')
> to some wrong value, then
> 
> tzap -r A
> ..HAS_LOCK
> ..HAS_LOCK
> ..HAS_LOCK
> 
> ^C
> 
> tzap -r B
> ..HAS_LOCK
> ....NO LOCK

Maybe the lock bit in the demod's status register isn't reset after
FE_SET_FRONTEND, but only after the demod gave up syncing with the
new parameters. If so, it would be a bug in the frontend drivers,
not in dvb_frontend.c.

Johannes