Re: Restricting a particular dvb card from tuning to channels with a selected modulation

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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. 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, 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. The patches are inline below:

--- dvbdevice.c.orig   2010-02-21 19:10:35.000000000 +0200
+++ dvbdevice.c   2010-04-05 17:20:06.080525344 +0300
@@ -872,8 +872,12 @@
 {
   if (!ProvidesSource(Channel->Source()))
      return false; // doesn't provide source
-  if (!cSource::IsSat(Channel->Source()))
+  if (!cSource::IsSat(Channel->Source())) {
+     cDvbTransponderParameters dtp(Channel->Parameters());
+ if (dtp.Modulation() == QAM_256 && !(frontendInfo.caps & FE_CAN_QAM_256))
+        return false;
return DeviceHooksProvidesTransponder(Channel); // source is sufficient for non sat
+  }
   cDvbTransponderParameters dtp(Channel->Parameters());
   if (frontendType == SYS_DVBS && dtp.System() == SYS_DVBS2)
return false; // requires modulation system which frontend doesn't provide

--- v4l-dvb/linux/drivers/media/dvb/frontends/tda10023.c.orig 2010-04-05 15:28:22.605844128 +0300 +++ v4l-dvb/linux/drivers/media/dvb/frontends/tda10023.c 2010-04-05 15:27:54.934343796 +0300
@@ -553,7 +553,7 @@
    #endif
       .caps = 0x400 | //FE_CAN_QAM_4
          FE_CAN_QAM_16 | FE_CAN_QAM_32 | FE_CAN_QAM_64 |
-         FE_CAN_QAM_128 | FE_CAN_QAM_256 |
+         FE_CAN_QAM_128 | //FE_CAN_QAM_256 |
          FE_CAN_FEC_AUTO
    },

-Petri

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