On 05/05/2011 12:21 PM, Ralph Metzler wrote:
> Hi,
>
> since it seems devices with several delivery systems can be queried
> with one command:
>
> Andreas Oberritter writes:
> > > Of course it does since it is not feasible to use the same adapter
> > > number even on the same card when it provides multi-standard
> > > frontends which share dvr and demux devices. E.g., frontend0 and
> > > frontend1 can belong to the same demod which can be DVB-C and -T
> > > (or other combinations, some demods can even do DVB-C/T/S2).
> >
> > There's absolutely no need to have more than one frontend device per
> > demod. Just add two commands, one to query the possible delivery systems
> > and one to switch the system. Why would you need more than one device
> > node at all, if you can only use one delivery system at a time?
>
> can somebody tell me how this is done and how it has to be supported
> in the demod driver?
Such commands don't exist yet and therefore need to be added as required.
For the Dreambox, we're currently using a proprietary interface to switch
between C and T, when the frontend is closed.
For an implementation within the bounds of the API, the device must not
be closed. Hence, I'd propose something like the following:
- In the driver, implement the set_property callback. For the property
DTV_DELIVERY_SYSTEM, do whatever is required to change the delivery
system if required, e.g.:
- Add and call a function to pause the frontend thread.
- Call fe->ops->sleep(fe) et al. (c.f. dvb_powerdown_on_sleep).
- Set fe->ops to the new struct dvb_frontend_ops pointer.
- Call dvb_frontend_reinitialise(fe);
- Fix dvb_frontend_thread() to not call ops.set_voltage and
ops.set_tone unless non-null.
- Add an S2API property DTV_DELIVERY_SYSTEMS which can be used
to query the available delivery systems.
- Add a default 'get_property' implementation to dvb_frontend.c:
- tvp->u.buffer.data[0] = c->delivery_system;
tvp->u.buffer.len = 1;
- Implement ops.get_property in the driver, e.g.:
tvp->u.buffer.data[0] = SYS_DVBC_ANNEX_AC;
tvp->u.buffer.data[1] = SYS_DVBT;
tvp->u.buffer.data[2] = SYS_DVBT2;
tvp->u.buffer.len = 3;
- Increment minor API version.
Regards,
Andreas
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