[linux-dvb] Asys P7131 Hybrid: DVB out of range
xyzzy at speakeasy.org
Thu Sep 6 17:47:49 CEST 2007
On Thu, 6 Sep 2007, Mauro Carvalho Chehab wrote:
> > > The limits are comming from the tda10046 info. I think the correct thing
> > > to do here is to not have the tda1004x driver define frequency limits, as
> > > it's the tuner that has the limits.
> > Nak. You must not remove these limits unless you make sure
> > that all tuner drivers which might be attached to this demod
> > have non-zero frequency limits.
So the incorrect limits should be left there? That isn't right either.
> IMO, the better would be not to initialize frequency ranges at the
> demods (since this is tuner stuff).
At least for many demods, the frequency range supported is determined by
the tuner. One could have a chip that combines the demod and tuner
functions, or a system where the demod is somehow involved in tuning and
has some limit. But that is not the case here.
> If you are afraid of having a tuner driver with improper values, add a
> check can be added, at dvb frontend core, to use the maximum allowed
> frequency range, if frequency_max is not defined. The better, however,
> is to fix the tuner drivers without frequency limits.
This would be easy to do. There is already a function,
dvb_frontend_get_frequeny_limits(), that does this. It prints a warning
message if neither the demod nor the tuner define a limit. In this case,
it returns zero for the max frequency, so any attempt to tune with a driver
broken like this will fail. It could easily return ULONG_MAX in this case,
so tuning would work but there would still be the warning message.
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