[linux-dvb] Re: Are frontend events queued?

[Holger Waechtler <holger@qanu.de>]

Wolfgang Fritz wrote:
> Hello,
>
> I'm trying to get some facts about the infamous "video data stream
> broken" error in VDR.
>
> The following modified code from VDR-1.3.10/dvbdevice.c cDvbTuner::Action
>
>   active = true;
>   while (active) {
>         ....
>         if (tunerStatus == tsTuned) {
>            fe_status_t status = fe_status_t(0);
>            CHECK(ioctl(fd_frontend, FE_READ_STATUS, &status));
>            if (status & FE_HAS_LOCK) {
>               tunerStatus = tsLocked;
> 	      dsyslog ("Frontend %d locked", cardIndex);
> 	      }
>            }
>         if (tunerStatus != tsIdle) {
>            dvb_frontend_event event;
>            if (ioctl(fd_frontend, FE_GET_EVENT, &event) == 0) {
> 	      dsyslog ("Event on frontend %d: %02x", cardIndex, event.status);
>               if (event.status & FE_REINIT) {
>                  tunerStatus = tsSet;
>                  esyslog("ERROR: frontend %d was reinitialized -
> re-tuning", cardIndex);
>                  continue;
>                  }
>               }
>            }
>      ....
>         bool fast = (tunerStatus == tsTuned) || (ciHandler &&
> (time(NULL) - startTime < 20));
>         newSet.TimedWait(mutex, fast ? 100 : 1000);
>         }
>
> sometimes gives the following output:
>
> Jul 21 19:06:21 vdr vdr[1697]: Event on frontend 1: 00
> Jul 21 19:06:21 vdr vdr[1697]: Frontend 1 locked
> Jul 21 19:06:21 vdr vdr[1697]: Event on frontend 1: 03
> Jul 21 19:06:22 vdr vdr[1697]: Event on frontend 1: 1f
>
> What does this mean?
>
> - Did the frontend really lose lock for a short time?
yes.

Frontend events are queued but a while ago there were a discussion (I 
believe on this list but I'm not perfectly sure... maybe it was in the 
#dbox2 irc - ) where we ended in consens that it does not really makes 
sense from a userspace point of view to queue the events and the event 
ringbuffer code might basically vanish.

Also the frontend thread handling might get simpler in this case.

Holger