[linux-dvb] Lockups with cx2388x cards

peter at naiadhome.com peter at naiadhome.com
Fri Jan 11 11:32:53 CET 2008

Steven Toth wrote:
> Peter Martin wrote:
>> I have a couple of Hauppauge cards (Nova-T using the cx2388x and a Nova 
>> Plus, again using an cx2388x) in an industrial motherboard (an Axiomtek 
>> ATX6022-14G) which is causing me some grief. After a short time I am 
>> getting both cards locking up (no DMA) at the same time.
> Does it happen with only a single card active in the system?
Yes it does. If I start streaming from one card, it runs for a few minutes, then I get the timeout. I am then unable to start streaming from the other card after this. I will try a single card in the motherboard later.

> Have you tried the cards on other motherboards and do they operate 
> successfully without error?
Both these cards work fine in other motherboards, indeed they work with up to 5 cards for extended periods.

>> In order to get these cards working at all in this configuration, I have 
>> re-arranged the SRAM and increased the FIFO size in cx88-core.c to 
>> 0x4800 bytes, and disabled all the other channels (video, audio etc), 
>> which has cured the FIFO overflow errors I was getting ( general errors: 
>> 0x00000100), but the cards still lock up. The cards can run from between 
>> 5 seconds and 30 minutes before the lockup. I also get the lockups with 
>> the stock code, so I am happy that my SRAM chganges have not broken 
>> anything.
> IIRC, the fifo is pretty small (resulting in potential short latency 
> issues). This could be compounded with a busy DMA bus and short fifo's 
> both competing for the same DMA queue resource. I suspect increasing the 
> fifo really just masks the real DMA contension issue.
Sounds plausible. Since the failure of one card affects the other card(s) then I suspect you are right and there is a common DMA problem here. Any suggestions as to how I can look for this, I am a relative newbie to debugging PC systems at this level. FWIW, the PCI bridge is a Pericom P17C 8150B.

> What else is happening DMA wise in your system?
Not a lot of other DMA activity. A bit of disk IO for logging, and and < 100Kbps for ethernet, but this is all being done on the controlling SBC anyway which is behind the Pericom bridge.


> - Steve

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