[linux-dvb] DVB API update

Felix Domke tmbinc at elitedvb.net
Tue Sep 18 18:12:13 CEST 2007

Manu Abraham wrote:
>> I'm not against mmap, I'm against using development resources for
>> implementing it. I can't see the big show-stopper in this issue.
>> So, seriously: Is there anybody here who *needs* this, based on his own
>> experience?
>> If yes, I'll might change my mind.
> I think it would be nice to have it.
Yes, it would be nice.

But do you NEED it? Is it a show-stopper for you? Do you have a scenario
which doesn't work because of THIS?

>>> No, not throwing away anything, see my reply to Rainer. The newer
>>> features will not be available with the older apps, that's all. You can
>>> use the same drivers too. Backward compatibility is achieved by keeping
>>> an additional set of ioctl's, so the old stuff will work as it is.
>> Will older hardware drivers be compatible with a new dvb-core (more than
>> maybe changing some identifiers)?
> As it is, without any change. I think Johannes did the great job of
> confusing people.
Don't get personal.

Unstable driver APIs are a huge issue for non-mainstream hardware. Let's
do our best to keep devices without active maintainers supported. V4
would have killed them, so i only want to be sure that your "api
updates" won't.

>> My approach is to add a "DMX_ADD_PID" ioctl, similar to DMX_SET_FILTER.
>> [...]
> This sounds fine to me.

>>  * "The current API doesn't allow you to do simple TS filters."
>> Again, in http://www.spinics.net/lists/linux-dvb/msg09258.html I came up
>> with my solution, however people noted that this might break FF cards
>> due. This can probably be avoided by using a better value for DMX_TAP_TS.
>> Note that the dvb-core implementation is trivial, as hardware drivers
>> are already supporting TS filtering. It's just not exposed to userspace.
> Mostly USB devices, afaik. Any other devices that you would like to
> mention ?
I don't understand this sentence. Any device not ignoring (a not-set)
TS_PAYLOAD_ONLY-flag should be compatible.

>>  * "The current API doesn't allow you to tune into -S2 transponders."
> We have solved this one already, drivers also exists, people watch S2
> What i pushed out last, is out here:
> http://jusst.de/manu/04-Jul-07/stb0899.tar.bz2
ok. I don't like any part of the API (FE_SET_FRONTEND) to be obsoleted,
but ok, I can live with it. Please specify a bit more explictely which
parts of the API are mutually exclusive (FE_SET_FRONTEND vs.
DVBFE_SET_PARAMS). why are some IOCTLs called DVBFE_ and others FE_?

BTW, this doesn't hold my "backward compatibility" request - if an
application wants to tune a dvb-s transponder with the new api
(DVBFE_SET_PARAMS), it won't run against an old api (which only
implements FE_SET_FRONTEND, but could technically tune). But it seems
that nobody else cares about this.


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