[linux-dvb] Why my binary-only Win95 closed-source drivers trump your puny free-as-in-beer etc. [was: Re: why (etc.)]

Paul Chubb paulc at singlespoon.org.au
Sat Sep 13 12:35:57 CEST 2008

delightful post. I am not sure I am able to answer all your questions 
because my experience is strictly limited to what I have done in the 
last three weeks. My experience is two surmountable incompatibilities. 
Being a newbie I may have misunderstood what I am seeing but:

1) My take is that the mcentral.de tree was originally based somewhere 
around 2.6.22. At some stage the functionality in videobuf_core.c was 
replaced by video-buf-dvb.c. This meant that when you compile against 
the 2.6.22 headers it works fine but still loads the videobuf_core 
module from the previous module set. Once you get to 2.6.24 it still 
loads videobuf_core, however now you get a lot of symbol issues when it 
loads and ultimately the driver for the card didn't work. This was 
simply fixed by removing all the old drivers in the drivers/media/video 

2) The v4l-dvb tree has complex firmware loading logic in tuner-xc2028.c 
that is tied to a single file that has lots of firmware modules in it. 
the mcentral.de tree has that code replaced by a new xc3028-tuner module 
that is designed to load individual fw files. Mr Rechberger managed to 
get original firmware from Xcieve.

So either could be fixed, and I fixed the first. I could have fixed the 
second by investing more time. But I don't think that is why people talk 
about incompatibility between the two.

Cheers Paul
barry bouwsma wrote:
> Bow down before the might of my hardware that I can't use on
> anything later than an LSI-11-based machine!  Replies there ------>
> plz thx okbye
> --- On Sat, 9/13/08, Paul Chubb <paulc at singlespoon.org.au> wrote:
>> The third attempt by a Czech programmer succeeded, however it is 
>> dependent on the mcentral.de tree and the author appears to
> I have a serious question.  Really.  I mean it.
> I want factual answers.  No flames.  If your native language
> is not english, feel free to reply in personal mail in your
> native language, and I will try to make sense of it -- sometimes
> I feel that non-english speakers here would be far more effective
> in their native language, as anyone who has heard or read me
> fumbling through their native languange (english included) will
> agree.
> I periodically build the drivers from recent em28xx-new against
> a recent kernel, and pass the needed patches upstream.  While
> I have an EM288x device, it's not yet supported, so I can't
> actually test my hacks.
> I've just now downloaded the mcentral v4l-dvb source, in an
> attempt to compile (notice I said nothing about functionality)
> it against a recent kernel.  My observation so far is that it
> has heaps of backwards-compatibility, and lacks a few recent
> changes that I'm hoping to merge in.  (`Hope' the operative
> word)
> Otherwise I really don't pay attention to the details of the
> drivers and their use, probably the reason for my question.
> You can bet that as soon as Markus has time to write support
> for the demodulators and such, that I'm going to try my hardest
> to get it to work with a stock linux kernel.
> Can you, or someone, explain the technical details of what needs
> to be done to a random, or a particular driver on mcentral, to
> get it into em28xx on linuxtv?  Or why it can't be done as is,
> as I see a slow addition of drivers to linuxtv over time?
> Or better yet, give me an example of code that won't fit into
> linuxtv from mcentral.  That might keep me quiet for a while.
> In spite of the fact that I may have the datasheet for one of
> the chips in my unsupported device, there is no way I'll be
> able to turn that into a driver, no matter how much mentoring
> or handholding I get, whereas I might be able to stumble my
> way through incompatibility issues with plenty of review.
> Maybe in ten years or so, in the event I'm still alive, I'd
> be able to whip together a driver free of the enforced DRM
> (not the broadcast norm DRM, hmmm, does that deserve a place
> in the digital-broadcasting API?)
>> I understand from recent posts to this list that many in the community 
>> are disturbed by the existence of mcentral.de. Well every person from 
>> now on who wants to run the Leadtek Winfast DTV1800H will be using that 
>> tree. Since the card is excellent value for what it is,
> This is the second time I've read about incompatibility (an
> either/or choice) between the trees.  That obviously isn't
> acceptable to me.  Can you or someone give a *technical only*
> overview of why this should be, so I can motivate myself to
> do what I can to make it should not be so?
> Again, no flames, minimal opinions, please.  Facts will be
> `rewarded' by an `effort' on my part to try to `benefit'
> everyone out there who wants additional `functionality', but
> no promises.
> Disclaimer:  if I don't make much sense, it's due to chronic
> sleep deprivation, in part.
> thanks,
> barry bouwsma

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