[linux-dvb] AW: Questions Round2

[Ralph Metzler <rjkm@metzlerbros.de>]

Florian Schirmer writes:
 > >> A) Copy all the dvb api soft dmx functions and hack them to use the
 > >> engine. This will result in lots of duplicate code.
 > 
 > >That's how it is meant to be. 
 > >The kernel demux layer is supposed to be implemented for each hardware
 > separately. 
 > >We only used the software demux module for the AV7110 because it is 
 > >lacking some features like piping data from user space through the
 > hardware demux. 
 > >For other hardware we wrote a new demux module. 
 > >I guess some of the more administrative code could be shared to 
 > >avoid duplication. 
 > 
 > I see an middleware api as a kind of HAL. The hardware tells the
 > middleware layer what it is capable of doing. If there are features the

That's how it already is supposed to be. 
The kernel API layer already tells the lower one what it can do by 
having the function pointers set to 0 or not.
There should be some checking for this added to dmxdev et al.

 > hw does not support and the user wants to use, the middleware layer
 > jumps in that place by providing an own (probably) slower emulation of
 > the missing features.

This is supposed to be done by stacking kernel API implementations.
There just is no example of an implementation which does it that 
way yet.

 
 > E.g. if the DMX claims not to be capable of section filtering the
 > middleware should _not_ try to request section feeds from the dmx. This

Correct, but this (not having the call) should only happen 
if there is no software emulation layer in place. 


Ralph


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