[vdr] VDR and Hybrid DVB Cards ( was "HVR 4000 drivers broken - adapter0/frontend1 busy" in linux-media list )

Klaus Schmidinger Klaus.Schmidinger at tvdr.de
Fri Nov 18 23:53:39 CET 2011

On 18.11.2011 23:40, Mika Laitio wrote:
>> I've received an email from Manu Abraham, informing
>> me that he intends to change the driver in such a way that there will
>> always
>> be only *one* frontend, even if it can handle multiple delivery systems.
>> So every frontend an adapter will provide will always be useable
>> independent
>> of all other frontends of that adapter.
>> Personally, I like this method more than having separate frontends for
>> each delivery system, and having to manage access between them.
>> Just wanted to let you know that the official implementation in VDR
>> (most likely after version 2.0) will go a different way than your patch.
> I am wondering what's the reason of breaking this current rule as it
> sounded so clear...So if cards all delivery systems are mapped as an
> adapters under same frontend, there must be a some method for querying
> which of those adapters are tied together. Did Manu say whether that
> info can be get via dev tree, via sysfs or by using some new ioctl?

That was my misunderstanding in the beginning, too, and it resulted
in a lengthy discussion with Manu ;-)

 From what I understood, every physical device (i.e. a DVB PCI card, a USB
receiver or whatever) will be exactly *one* adapter. If an adapter provides
several delivery systems (like, for instance, DVB-S and DVB-T) and only
one of these can be used at a time, there will be *one* frontend that needs
to be switched to the desired delivery system before tuning to a transponder.
A new ioctl() will allow the application to query which and how many
delivery systems a frontend provides.
If the adapter has like two DVB-S tuners that can be used simultaneously,
then it will have two separate frontends.

> And if the patch wont go in, it means that hvr-4000 owners needs to
> maintain in addition of the vdr-patch, also a patches for all plugins
> that the patch breaks :-(. On the other hand, if the patch would be
> accepted to vdr before 2.0, I am sure that all plugi-ns would be adapter
> to work in couple of weeks to work with the new interfaces.

 From what I understand at this time I don't see why implementing
multi-frontend support would break any plugins. Lars' patch apparently
does, but my goal would be to make this totally seemless, so plugins
wouldn't even notice.

Right now I have only very little (if any) time to work on VDR,
because my daytime job requires all my attention. This will change
by the end of the year, and then we'll see whether Manu's patch has
made it into the driver and whether this can be used for VDR 2.0.

Personally I hope Manu's implementation gets adopted, because I find
it very straightforward.


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