[linux-dvb] Re: Summary (to Holger :-)

[Holger Waechtler <holger@convergence.de>]

Dennis Noordsij wrote:
>>>* Where is the timeout specified for deciding wether or not there is a
>>>lock and before trying a different frequency? I can see many (inserted)
>>>printk's "trying freq xxxxx Hz", "trying freq yyyyy Hz" log messages,
>>>many times without locking, and then suddently it will lock on freq xxxx
>>>which has already been tried a dozen times before without success.
>>
>>where have you seen these printk's?
> 
> 
> I inserted them, I think in tuner_tv_set_freq.
> 
> Like I said, zigzagging etc works very well for me in REL-0-9-2, so it can 
> obviously be done very effectively, I just haven't had much luck with it in 
> HEAD yet :/
> 
> But according to the tuner_tv_set_freq printk's, it will take several attempts 
> at identical frequencies and settings to acquire a lock, so I am wondering 
> where it waits for the lock and decides wether or not to "move on". Say it 
> zigzags around a center frequency, it will pass the center frequency a few 
> times (going up, going down, etc), and then eventually it will lock to that 
> frequency (which has been tried several times right before). 

please enable the printk() in dvb_frontend.c, 
dvb_frontend_set_parameters(), line 352. Maybe you want to add another 
printk() in every function that calls dvb_frontend_set_parameters().


> It would seem a faster approach would be to forego most of the zigzagging 
> (within 250kHz or center frequency is as a far as it might have a change of 
> tuning in), and try more persistantly to lock in the smaller frequency 
> window. 

This could fail on hot summer days when the LNB drift is really high.

Holger



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