[linux-dvb] Re: Twinhan DVB-T: Works, what's next?

[Jamie Honan <jhonan@optusnet.com.au>]

> >Now I want to make a proper frontend driver for it.
> >
> >I started with Twinhan DVB-S "dst" frontend and butchered
> >it to death in the process. There are a some things in 
> >common between the two but there are some subtle differences.
> >It may be easier for me to do a completely new frontend for 
> >this card only and leave dst as it is as I have no way of 
> >testing my changes with the satellite version.
> >The frontend is going to be quite small and simple really.
> >bttv and dvb-bt8xx will do most of the hard work, I only need
> >to set up the tuner.
> >
> >The card supports 2 commands (those that I'm aware of).
> >One is SET_TUNER, it takes frequency and bandwidth and returns
> >non-zero if the tuner has a lock, 0 otherwise. The CPU on board
> >takes care of the rest. It can take upto 1 second to complete. 
> >The other command is GET_STATUS, it returns 3 1-byte values 
> >somehow related to signal strength and quality. The first byte 
> >is zero if the tuner is not locked onto signal and non-zero 
> >otherwise. Apart from that I've no idea how to interpret them yet.
> >
> >I have a few questions
> >
> >
> >* Are these 2 commands above enough to control the tuner 
> >or do I need to dig deeper?

You'd need almost everything else in dst.c to do with i2c and
gpio control if you want it to work with dvb.

I've made a preliminary version incorporating all your changes
for TV in a pre-cvs commit on my
http://members.optusnet.com.au/jhonan/dst. I guess my email to you
about this crossed over with this message.

Because of the great commonality I think it is better to do this
all in one place. 99% of it is the same.
I would prefer to have you take what I've done, critise and modify.

> >* My card only requires frequency and bandwidth. I can
> >ignore all the extra parameters in SET_FRONTEND but what 
> >should I return in GET_FRONTEND?
> 
> The appropriate XXX_AUTO values, so it's possible to tune again with the 
> values you obtained.

OK, this probably needs to be fixed.

> >* What is the scale of SNR, BER and signal strength
> >values as returned by the frontend? Where are they used?
> 
> Read cvs.linuxtv.org/DVB/doc/HOWTO-use-the-frontend-api for an 
> explanation.
> 
> >Do I have to implement all of them?
> 
> :) all the hardware supports...
> or: if you don't have the required info to implement them you simply 
> can't do it...
> 
> >* Anything else I'm missing?
> >
> >One last thing, I guess I will need CVS access sometines soon.
> 
> No problem, just send Johannes, Michael or me your ssh2 key and we'll 
> create an account for you.

I personally feel a unified driver is by far the better way for now.

Bear in mind that Twinhan now has half a dozen versions of this card
now, a fix for one would have to be replicated.

Jamie


-- 
Info:
To unsubscribe send a mail to ecartis@linuxtv.org with "unsubscribe linux-dvb" as subject.