Hans Verkuil wrote:
> The only thing I know of that causes artefacts etc. is de DMA error. 
> Once that occurs the only 'fix' at this moment is to reboot.
> 
I too noticed that the errors would continue past the 'damaged' segment, and 
also from one recording to the next. Can't we reset the chip (reloading the 
driver) or similar?

I have not experimented with this myself yet.

Thank you for running the 'special' frequency policy manager - it is about 
the same that I intended to run .-)

Is there any benefit in me reproducing this to confirm that the changing CPU 
speed in mid-DMA can cause the errors?

If not, I can return to running with PIO, and reenable the cpuspeed function.

Yours,
-S

>       Hans
> 
> On Sunday 20 August 2006 22:39, Michael Zanetti wrote:
>> Hello,
>>
>> I'm back home now. I just tried disabling CPU Frequency scaling
>> again. The machine is running now for about 3 hours. I haven't seen
>> any DMA error yet but I can see already artefacts and corrupted mpg
>> video. Usually this happens just before the DMA errors come up. Do
>> you have this behavior on your setups? Could someone with a working
>> setup please attach or upload a kernel config file? I hope I can find
>> out some more settings that cause this problem.
>>
>> Michael
>>
>> Am 20.08.2006 um 21:39 schrieb John Drescher:
>>>> I've finally managed to reproduce the DMA error reliably and
>>>> quickly using the following shell script on my dual AMD:
>>>>
>>>> #!/bin/sh
>>>> cd /sys/devices/system/cpu
>>>> echo userspace >cpu0/cpufreq/scaling_governor
>>>> echo userspace >cpu1/cpufreq/scaling_governor
>>>> while true; do \
>>>>         echo 2200000 >cpu0/cpufreq/scaling_setspeed; \
>>>>         echo 2200000 >cpu1/cpufreq/scaling_setspeed; \
>>>>         sleep 0.3; \
>>>>         echo 1000000 >cpu0/cpufreq/scaling_setspeed; \
>>>>         echo 1000000 >cpu1/cpufreq/scaling_setspeed; \
>>>>         sleep 0.3; \
>>>> done
>>>>
>>>> For some reason powernowd triggers the bug only very rarely, but
>>>> this shell script is very effective.
>>> Thanks for the script. I got "dmabug.sh: line 9:
>>> cpu0/cpufreq/scaling_setspeed: Permission denied" errors when I
>>> tried that as root so I guess I'll have to dig a little deaper into
>>> my kernel config to see why this is happening.
>>>
>>> John
>>>
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-- 
Simen Thoresen, Dolphin ICS

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