[linux-dvb] Problems with KNC1 DVB-C

Rudy Zijlstra rudy at grumpydevil.homelinux.org
Mon Apr 30 15:56:30 CEST 2007

Rudy Zijlstra wrote:
> e9hack wrote:
>> Oliver Endriss wrote:
>>> Apparently it works in polling mode, but not in interrupt mode. Why?
>>> Can someone else confirm problems with this card type
>>> (Terratec Cinergy 1200 DVB-C, sub-system 0x153b:0x1156)?
>>> Now I consider the following options:
>>> - Add a module parameter to disable irq mode.
>>> - Turn off irq mode for card type 0x153b:0x1156.
>>> - Turn off irq mode for the TDA10021 frontend.
>>> - Revert to polling mode for all cards.
>>> :-(
>>> Any opinions?
>> The windows driver uses a reduced i2c bit rate. I've reduced the bit 
>> rate with the patch for the new DVB-C cards.
>> Possible, it does solve the problem.
>> - Hartmut
> Original start configuration:
> dual PIII with KNC-1, as well as 2 DVB-S cards, running
> Was running with mild problems: the CAM on the KNC-1 was loosing sync.
> P4 with Terratec Synergy, mostly being used for TS recordings. No 
> apparent problems, running older kernel.
> Then i got problems with the KNC-1, in that suddenly i could still 
> tune but no longer got any data off the card.
> Action 1: swap KNC-1 and Terratec.
> Result 1: PIII system still giving same problems
> P4 system with KNC-1 doing well.
> Action2:
> thinking i was facing some weird application problem, i took an older 
> Mythtv, build that on the P4 as a separate test system for DVB-C and 
> slowly upgraded to most recent SVN head.
> Result2:
> no problem found
> Action3:
> upgrade the PIII to
> Result3:
> The DVB-S cards work quit well (although diseqc seems to give 
> intermitent problems), Terratec lost interupts, showing in i2c 
> problems (see this thread).
> Action4:
> Implement patch from Oliver Endriss.
> Result4:
> On the dual PIII i2c works again, tuning works but i cannot get any 
> data from the card......
> Action5:
> upgrade the P4 to unpatched
> Result5:
> The P4 with the KNC-1 works without problems.
> At request i am willing to swap the Terratec and the KNC-1 to double 
> verify the terratec also behaves well in the P4 with unpatched
> Provisional conclusion:
> The dual PIII is having interupt problems, most likely at least one 
> PCI slot is no longer working correctly on interrupt level.
> I am saying "at least one PCI" as i suspect the intermittent diseqc 
> problems can also be caused by missing interupts.
> Next action not yet known....
> If anyone has a suggestion on how to test for problems on the other 
> PCI slots, i'd be happy to know that.
> Cheers,
> Rudy
Some additional information.

Changing the cards in PCI slots made no difference. Then i remembered i 
had disabled ACPI on this system, after previous IRQ problems. Enabling 
ACPI resulted in better behaviour.

After a while i still seem to get lost interrupts though. (i get hickups 
in the stream).

So it seems a Netfinity 5000 can handle 2 DVB cards, and with some 
trouble 3. But above 2 it seems to get less stable. Unless this is a 
kernel level IRQ routing problem?



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