[linux-dvb] Re: AW: Questions Round2

[Holger Waechtler <holger@convergence.de>]

Florian Schirmer wrote:
> 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]

just my opinion.

Holger



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