[linux-dvb] Re: Full featured card summary

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

On Sunday 14 March 2004 22:47, Holger Waechtler wrote:
> On Sunday 14 March 2004 23:46, Andrew de Quincey wrote:
> > On Sunday 14 March 2004 22:36, Holger Waechtler wrote:
> > > As soon you submit the polarisation selection command (VOLTAGE_13V or
> > > VOLTAGE_18V) you already powered up the LNB. The only important thing
> > > is to maintain the delay times required by the spec, the diseqc.c
> > > example shows how this can get implemented.
> >
> > I think the problem was they're using DISEQC 1.0/2.0 switches, but
> > weren't using the older voltage-based polarisation selection commands,
> > assuming that the frontend would have automatically applied some power to
> > the LNB (BTW: I do know the sequence in the DISEQC spec says you should
> > specify the voltage; I use that exact sequence in my code).
>
> The DiSEqC spec explicitly requires you to set up a bus voltage of 13 or
> 18V and wait a little before submitting any command.
>
> > I suppose its a matter of how tolerant we want to be of userspace
> > programs.. I mean, we already turn OFF the LNB power automatically, why
> > not turn it on as well?
>
> we do, a LNB power switch is automatically enabled as soon a voltage != 0V
> is specified by all drivers I'm aware of. Did not checked the latest
> changes though, if the VES1x93 does not do so anymore it needs to get
> fixed, you should set the GPIO line high that is connected to the LNBP as
> soon any bus voltage != 0V is requested.

Yeah, it does. The issue is as follows:

driver 1.0.1: ves1x93 set the LNB voltage to 13v as soon as the driver was 
loaded. When you select the voltage, it sets the correct GPIO

driver 1.1.0: ves1x93 was changed so it left the voltage at 0v when the driver 
was loaded. When you select the voltage, it sets the correct GPIO

The problem with 1.1.0 is VDR isn't doing the full DISEQC init sequence, and 
so no voltage was ever being sent to the LNB. So its really a fixed driver 
bug clashing with an issue in VDR.


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