[linux-dvb] Re: Full featured card summary

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Andrew de Quincey wrote:
> 
> 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.

As of version 1.3.6 VDR explicitly turns on the LNB power at startup (which
I believe the driver should do when the frontend is opened), but that didn't
fix the actual DiSEqC problem (unreliable switching).

Klaus


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