[linux-dvb] Re: tda1004x slow freq switch times

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Thursday 02 Dec 2004 09:32, Peter Siering wrote:
> Hi,
>
> there has been some discussion on slow channel switching times (>10s)
> with a tda1004x frontend (Nova/Budget-T boards). I've compared two
> different driver releases last night - where I started:
>
> - dvb driver 1.0.x (pretty old I know): tuning fast, even when switching
> frequency/transponder
>
> - dvb driver 1.1.1+y (dvb-kernel from cvs for 2.4): tuning slow, when
> switching frequency/transponder
>
> here are my findings:
>
> - if loading frontend module with tda1004x_debug with the newer driver I
> see multiple calls(?) to tda1004x_set_frequency and very slow channel
> switches (in VDR); if I use the old driver and set this option, I've
> seen just one of those calls and switching is fast
>
> - in a first attempt, I've tried to use the old frontend code with the
> new driver, but had no success (switching slowly)
>
> - afterwards I compared the dvb_frontend-code in 1.0.1 (cvs revision
> 1.55) with 1.1.1: there have been many changes since then so a
> overhauled tuning code, but using the debug options did not get me any
> further
>
> - this morning I played around with a special option
> "dvb_override_tune_delay" and voila: by changing this to 800 the time it
> takes to switch frequency/transponder gets close to the old driver (most
> of the time ;-)); I do not see multiple calls to tda1004x_set_frequency
> anymore.
>
> May someone confirm or reproduce this? (I've just tried it with one PC,
> 400 MHz PII)
>
> Does this point to a problem in the tuning code?

Yup, I'd forgotten to add the function pointer which does it, well spotted. 
Change is in CVS HEAD now.