[vdr] Restricting a particular dvb card from tuning to channels with a selected modulation

Klaus Schmidinger Klaus.Schmidinger at tvdr.de
Mon Apr 5 22:18:48 CEST 2010

On 05.04.2010 20:55, Petri Helin wrote:
> On 04/05/2010 12:57 PM, Klaus Schmidinger wrote:
>> On 05.04.2010 00:55, Teemu Rantanen wrote:
>>> Hi,
>>> There's a new version of the patch implemented as a plugin. It seems to
>>> work, but there are few things to notice:
>>> - Plugin does not cache which devices are Reddo devices, instead it
>>> probes sysfs every time QAM256 channel is being tuned into (on any
>>> device). It would be nice if cDeviceHook added a mechanism for a hook to
>>> store context for each device. Hooking into device probe (like full
>>> feature card plugin does) would be much nicer way, but it would
>>> interfere with other plugins which need the same mechanism.
>> The proper way of doing this is to check the modulation types
>> in cDvbDevice::ProvidesTransponder(), as in the attached patch (which
>> will
>> be part of VDR 1.7.15). If the "reddo" driver doesn't set the
>> FE_CAN_QAM_256
>> flag correctly, it needs to be fixed there.
> I used your patch as an example and created a simple test patch for
> dvb-c (I think yours is for dvb-s(2) only) in order to test the
> approach.

You're right. I guess the attached version should cover all frontend types.

> I also disabled FE_CAN_QAM256 from the driver. After that VDR
> no longer used Reddo for QAM256 channels as expected. The approach is
> very limited: It disables QAM256 for the every TDA10023 frontend, not
> just for Reddo's,

Well, then the driver needs to make a finer distinction and *properly*
set FE_CAN_QAM256.

> and it doesn't make VDR to prefer Reddo for non QAM256
> channels, which would make sense in order to keep QAM256 channels
> available as much as possible.

First the driver needs to properly report whether a device can handle
a given modulation type. Then VDR can decide whether to use that
device for a channel requiring that modulation. *Then* we can talk
sparing such devices for recordings ;-)

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