[linux-dvb] [PATCH] Future of DVB-S2

Steven Toth stoth at linuxtv.org
Fri Aug 29 18:03:02 CEST 2008

Michael Krufky wrote:
> On Fri, Aug 29, 2008 at 11:43 AM, Hans Werner <HWerner4 at gmx.de> wrote:
>>> ... and yes, many people understand you.
>> :) Thanks to everyone who replied so far. I am glad people care about this.
>>>> We know all about the "coding in your free time" and we can only have
>>>> the highest respect for that, but the drivers are completely abandonded,
>>>> and that's how we feel, too.
>>> No, and that's my HVR4000 code you're talking about (and the good work
>>> of Darron Broad, which was then picked up by Igor). The driver is
>>> marginalized, it's not abandoned.
>> I hope your and Darron's drivers (http://dev.kewl.org/hauppauge) are not seen as
>> marginalized. The multifrontend (MFE) patch by you and Darron is the driver that I
>> actually *use* for watching TV. It works nicely with Kaffeine without modification. And I,
>> for one, appreciate your sane approach and the simplicity of the techniques you used to
>> add DVB-S2 support (using sysctls for the SFE driver, and wrapping two ioctls to pull in
>> extra parameters for the MFE driver). If the kernel API is changed sensibly it should be
>> easy and quick to adapt your drivers to fit in.
>>> The HVR4000 situation is under review, the wheels are slowly turning....
>> If you are able to say anything about that I would be very interested.
>> Now, to show how simple I think all this could be, here is a PATCH implementing what
>> I think is the *minimal* API required to support DVB-S2.
>> Notes:
>> * same API structure, I just added some new enums and variables, nothing removed
>> * no changes required to any existing drivers (v4l-dvb still compiles)
>> * no changes required to existing applications (just need to be recompiled)
>> * no drivers, but I think the HVR4000 MFE patch could be easily adapted
>> I added the fe_caps2 enum because we're running out of bits in the capabilities bitfield.
>> More elegant would be to have separate bitfields for FEC capabilities and modulation
>> capabilities but that would require (easy) changes to (a lot of) drivers and applications.
>> Why should we not merge something simple like this immediately? This could have been done
>> years ago. If it takes several rounds of API upgrades to reach all the feature people want then
>> so be it, but a long journey begins with one step.
> This will break binary compatibility with existing apps.  You're right
> -- those apps will work with a recompile, but I believe that as a
> whole, the linux-dvb kernel and userspace developers alike are looking
> to avoid breaking binary compatibility.

Hans, thanks for your kind words.

I've seen patches similar to this from a number of people, but this only 
solves today's problem, it doesn't help with ISDB-T, DVB-H, CMMB, 
ATSC-MH etc.

As mkrufky says, it also breaks compatibility.

... as I say, the wheels are turning so keep watching this mailing list.

- Steve

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