Peter,

On Nov 22, 2006, at 2:45 AM, Peter Carlsson wrote:

>> Peter,
>
>> There are a whole host of things you can do to make it better. First
>> of all, when the errors started, had you made any changes to your
>> machine?
>
> I try as much as I can to not do any changes to the system, but there
> were some updates via apt-get.

Specifically, which updates did you get?

>> There are a couple of things that are known to exacerbate this issue:
>> enabling SMP on a HyperThreading or Multiple-Processors machine, raid
>> arrays, cpu frequency scaling, interrupt conflicts, bad PVR cards,
>> and bad RAM.
>
> I do have powernow-k8 installed, but it's been there all the time  
> without
> causing any noticable trouble. I also have powersaved installed but  
> haven't
> had the time to configure it.

There's an easy way to disable cpu frequency scaling, but you'll have  
to make sure that the powersave daemon is not running (kill it or  
disable it from running). If you would rather not have to recompile  
your kernel, you can just execute the following command every time  
you boot up the computer:

sudo echo performance > /sys/devices/system/cpu/cpu0/cpufreq/ 
scaling_governor

>
> In a desperate attempt to fix the problem I compiled the ivtv  
> source and it
> seems it installed drivers not needed by my system. I only use a  
> PVR-150.
> Is this output indicating something wrong? Could I remove some?
>
> htpc:~# lsmod | grep ivtv
> <snip>

You have not done anything wrong - all of these modules are necessary!

>> To better diagnose this issue, could you provide output from /proc/
>> interrupts and lspci -v?
>
> htpc:~# cat /proc/interrupts
> <snip>
> htpc:~# lspci -v
> <snip>

Well, at least your ivtv card is not sharing its IRQ. But it is the  
lowest IRQ, and your Serial ATA device has a high number of  
interrupts, which could be the culprit... do you have some kind of  
RAID or LVM array set up with multiple hard drives?

Since it seems as though this was just an issue with upgrading your  
OS, I would try disabling the cpu frequency scaling / powersave  
daemon first, as that is likely the culprit.

If that does not fix your problem, you can try tweaking your PCI  
latency timings, as some people have had luck with this in the past.  
There's a great article on how to do this at Gentoo's site:

http://www.gentoo.org/doc/en/articles/hardware-stability- 
p2.xml#doc_chap3

To adapt this guide for ivtv, I would set all your PCI devices (even  
audio) to a setting of 'b0' then set the ivtv card to 'ff'.

Hope this helps!
- Rick


> On Nov 21, 2006, at 3:18 PM, Peter Carlsson wrote:
>
>> Hello!
>>
>> A few days ago I had problems with the well known DMA errors
>> while running kernel 2.6.16 and ivtv 0.6.3.
>>
>> I have now upgraded my Debian system to kernel 2.6.18 and
>> ivtv 0.8.0 with the hope that the problems were fixed.
>>
>> Yesterday I successfully recorded a one hour show but today
>> the DMA error seems to still be here.
>>
>> Any suggestions are welcome!
>>
>> <snip>


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