[linux-dvb] Re: DVB-CI question

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Friday 26 March 2004 15:14, Peter Urbanec wrote:
> Andrew de Quincey wrote:
> >On Friday 26 March 2004 14:33, Klaus Schmidinger wrote:
> >>If it's not hard to do in userspace, why is it so hard in the driver?
> >>Why should every application implement this by itself? I'd say this
> >> should be done by the driver, and the applications shall exchange
> >> complete TPDU's with the driver.
> >
> >IMO, the driver should be as simple as possible. I don't think the CAM
> >interface benefits speed-wise from the reassembly being in the driver, so,
> >apart from saving a little bit of extra code in userspace I can't see any
> >good reason for the reassembly being in the kernel. Each app already has
> > to implement all the other layers of the EN50221 control protocol stack
> > itself; why not this extra bit as well?
>
> If I can chime in with a purely design based rationale...
>
> Why only think of this from the point of driver vs. application? I agree
> with Andrew that the driver should be as simple as possible. The less
> code one has to run in the kernel context the better. However, I don't
> particularly like the idea of each application having to reimplement the
> same basic code - someone  is likely to get it wrong.
>
> How about adding another layer? Take all this from the driver, but
> provide a library implementation that applications can dynamically link
> to to get the reassembly for free. That way you get the benefit of both
> worlds. You keep the driver simple and the application developer doesn't
> have to reinvent the wheel.

Yeah, I agree, thats *exactly* the way to do it. 


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