[linux-dvb] AW: Questions Round2

["Florian Schirmer" <jolt@tuxbox.org>]

Hi,

>> 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
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.

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
doens't make any sense since this will push all the HAL logic into
_every_ dmx driver. IMHO the middleware should simply ask the dmx for a
plain TS feed and route it through it's soft section filter.

What you pointed out is not a HAL, its a complete rewrite of middleware.
Is that really intentional? What is/was the reason for this kind of
decision?

>The question is if, when you use a general kernel demux module with
special 
>acceleration features, etc. (i.e. effectly adding 
>another layer), you will make it general enough for all kinds of
hardware.

As i have limited knowledge of other DVB STBs / cards, my implementation
probably wont fit to all kinds of hardware out there. That's the reason
why i ask about for oppinions first, then create a patch based on the
feedback i get. Later on i will ask about oppinions again (this time on
the patch itself).

If you or someone else thinks it wont fit to their hardware, feel free
to step forward and suggest a better version. As long as nobody is
forced to provide a feature or use a (specific) layer, all improvements
which push the API into the direction of beeing a HAL is IMHO a good
thing[tm]

Thanks!

Florian




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