[linux-dvb] [PATCH] cx24116 DVB-S modulation fix

Christophe Thommeret hftom at free.fr
Wed Oct 15 18:46:58 CEST 2008


Le Tuesday 14 October 2008 19:02:03 Darron Broad, vous avez écrit :
> In message <200810141451.02941.hftom at free.fr>, Christophe Thommeret wrote:
>
> LO
>
> >Le Tuesday 14 October 2008 12:29:49 Darron Broad, vous avez =E9crit=A0:
> >> In message <200810141133.36559.hftom at free.fr>, Christophe Thommeret
> >> wrote:
> >>
> >> hi
> >>
> >> >Hi,
> >> >
> >> >This patch makes cx24116 to behave like other dvb-s frontends.
> >>
> >> Unlike most DVB-S cards the those with a cx24116 use S2API
> >> this makes them somewhat different.
> >>
> >> >This is needed especially because QAM_AUTO is used in a lot of scan
> >> > file=
> >
> >s.
> >
> >> What scan files are you referring to? The
> >> cx24116 only does PSK, not AM. QAM_AUTO
> >> doesn't sound right. the cx24116 can't
> >> auto detect anything, but that's another
> >> story...
> >
> >dvbscan initial tuning data files for DVB-S don't have an entry for=20
> >modulation. So an app like kaffeine simply set modulation to QAM_AUTO.
> >Why not QPSK, you ask? Simply because DVB-S standard allows QPSK and
> > 16QAM.=
>
> It doesn't include modulation because QPSK is implied.
>
> >Maybe there is not a single 16QAM TP all over the world, but it's still
> > a=20 valid modulation for DVB-S.
>
> As is said, the cx24116 only does PSK.
>
> The driver should return unsupported for anything it can't do.
>
> If someone out there actually uses 16-QAM (who are you?) and that person
> switches to an adapter with a cx24116 they should be informed of error
> when tuning 16-QAM, not acceptance of something it doesn't support.
>
> >So, we set modulation to QAM_AUTO when it's unknown/unspecified, like
> > in=20 dvbscan files (those being also used by kaffeine). And it works
> > pretty well= ,=20
> >just because most dvb-s can only do QPSK and so force modulation to
> > QPSK=20 instead of returning a notsup.
> >See this as software QAM_AUTO :)
> >
> >P.S.
> >This is with s2api.
>
> When you use DVB-S delivery you should set the modulation to QPSK. If
> an end-user out there really needs 16-QAM then you should allow them
> the option to change it to QAM_16. I do not think this is going
> inconvenience many people.

Ok, you win :)

Other subject:
Would you accept some patch to enhance cx24116 pilot_auto emulation?

-- 
Christophe Thommeret




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